What Is Tempeh? A Beginner's Guide to This Fermented Food

 

Quick answer: Tempeh is a traditional Indonesian food made by fermenting cooked soyabeans with a culture, usually from the Rhizopus family, until a white network of mycelium binds them into a firm, sliceable block. It tastes nutty, earthy and savoury, and it’s usually sliced and cooked until golden.

Picture this.

You're standing in a shop, looking at a little block of something pale and speckled.

You turn the packet over.

You look at the ingredients.

You look at the picture.

And then you think:

"Okay… but what am I actually supposed to do with this?"

If that's you, don't worry.

And if you've never tried tempeh before, you're certainly not alone.

Tempeh is still relatively unfamiliar to many people in the UK. It can look a little strange when you first meet it: a firm block of whole soyabeans, held together by a delicate white network.

It doesn't immediately scream "eat me."

But there's something quite wonderful hiding inside that unassuming little block.

Because once you understand what tempeh is, how it's made and—perhaps most importantly—how to cook it, it starts to make a lot more sense.

And that's really what we want to do here.

No complicated food science. No pretending you've been eating tempeh your whole life. Just a friendly introduction.

So, let's start at the beginning.

So… what actually is tempeh?

Tempeh is a traditional Indonesian food made by fermenting cooked soyabeans.

The beans are mixed (inoculated) with a fermentation culture, usually from the Rhizopus family, and kept warm for roughly a day or two.

During that time, something rather remarkable happens.

A fine white network of mycelium grows through the beans and binds them together.

The loose soyabeans gradually become a firm, sliceable cake.

That's tempeh.

And that white covering you see?

That's the fermentation doing its job.

It can look surprising the first time you see it.

We know.

We've had plenty of conversations with people who have looked at a block of tempeh and asked:

"Is that supposed to be there?"

Yes.

Very much so.

Where did tempeh come from?

Tempeh comes from Indonesia, where it has been made and eaten for generations.

And this is one of the things we love most about it.

Tempeh isn't a food invented yesterday because someone decided the world needed another "plant-based protein."

It has a long history.

In Indonesia, tempeh has traditionally been part of everyday cooking.

It can be fried, grilled, stir-fried, cooked into curries, added to soups, crumbled into dishes or simply sliced and cooked until golden.

In other words, it's food.

Not a science experiment.

Not a special food reserved for people who follow a particular diet.

Just food.

And that's how we like to think about it too.

What actually happens when soyabeans become tempeh?

This is where fermentation gets really interesting.

The process begins with soyabeans.

They're soaked and cooked, then prepared for fermentation. A small amount of starter culture is introduced and the beans are kept warm while the fermentation develops.

Over roughly 25–48 hours, the mycelium grows around and between the beans, gradually binding them into that familiar white cake.

It sounds complicated.

But when you see it happening, there's something beautifully simple about it.

Beans, time and the right conditions give you tempeh.

Of course, getting those conditions right is where the real craft comes in.

Temperature matters.

Moisture matters.

Timing matters.

The condition of the beans matters.

And anyone who has ever made fermented food knows that sometimes you can do everything carefully and still have a batch teach you something new.

We certainly have.

That's part of what makes making tempeh so fascinating. (We wrote about it in A Week of Kitchen Mishaps.)

Why does tempeh look a little… fuzzy?

This is probably one of the first things people notice.

And understandably so.

The white covering can look unusual if you've never seen tempeh before.

But that white network is the mycelium produced by the fermentation culture.

It is what binds the beans together.

So if you open a fresh block of tempeh and see a beautiful white network holding the beans together, that's a good sign.

It means the fermentation has happened.

Think of it as nature's edible glue.

Although perhaps don't tell your children that part.

What does tempeh actually taste like?

This is probably the question we hear most often.

And the honest answer is:

It depends on how you cook it.

On its own, tempeh has a naturally nutty, earthy and savoury character.

It's much more substantial than tofu.

You can see the whole beans inside it, and when you slice it, you get a firm texture with a satisfying bite.

Then something rather lovely happens when you cook it.

Give it some heat.

A little oil.

Some seasoning.

Let the edges turn golden.

And suddenly that humble block becomes crisp, savoury and deeply satisfying.

This is why we often tell people who are trying tempeh for the first time:

Don't judge it by the block.

Cook it.

Give it a chance to show you what it can do.

Tempeh and tofu: aren't they basically the same thing?

No—and this is an easy mistake to make.

They're both made from soyabeans, but the way they're made is quite different.

Tofu is made from soya milk, which is coagulated and pressed into blocks.

Tempeh, on the other hand, keeps the whole soyabean and ferments it.

That difference gives them completely different personalities in the kitchen.

Tofu tends to be soft, smooth and relatively neutral.

Tempeh is firmer, more textured and naturally nutty and savoury.

Neither is "better."

They're simply different.

Think of tofu as the quiet one that happily takes on whatever flavours you give it.

Tempeh arrives with a little more personality of its own.

And that's exactly why we love it.

They're both soya-based and vegan-friendly, but they're made completely differently, and they behave completely differently in a pan.

*Figures are typical ranges and vary by brand. Check the pack of the product you’re buying.

Why is tempeh considered a nutritious food?

This is another reason tempeh has attracted so much attention.

Because it isn't just interesting—it is also naturally nutrient-dense.

Tempeh is a source of plant protein and fibre, while keeping the whole soybean rather than separating it into soy milk and solids.

Typical tempeh contains around 18–20g of protein per 100g, although the exact amount varies between products.

It also provides fibre, fats from the soyabean, and a range of vitamins and minerals.

But there's another interesting part.

Fermentation changes the soyabean.

The fermentation process breaks down some of the compounds present in the beans and can improve the availability of certain nutrients.

It also changes the texture and flavour.

So tempeh isn't simply "beans stuck together."

It is the result of a biological process that transforms the beans into something quite different.

That transformation is what makes it so fascinating to us.

Is tempeh actually good for you?

We think it's important to be sensible here.

Tempeh isn't a miracle food.

It's not going to fix everything that's wrong with your diet.

And we don't think food needs to make enormous promises to be worth eating.

What the research does show is that tempeh can be a nutritious part of a varied, plant-forward diet, particularly because it provides protein and fibre and because fermentation changes the nutritional characteristics of the soybean.

Research into fermented foods and their potential effects on gut health, blood lipids and other aspects of health is promising, but some areas still need larger and longer human studies.

So our philosophy is simple:

Eat good food. Eat a varied diet. Enjoy what you're eating.

Tempeh can be part of that.

And it happens to be delicious when you get it right.

Is tempeh vegan, gluten-free and allergen-friendly?

Traditional soyabean tempeh is plant-based, so yes, it’s usually vegan.

But always check the ingredients of the particular product you're buying.

Different producers can use different ingredients, grains or flavourings.

The same goes for gluten.

Plain soyabean tempeh made with appropriate ingredients can be gluten-free, but you should always check the packaging if you need to avoid gluten or have coeliac disease.

And if you have a soya allergy, tempeh made from soyabeans isn't suitable for you.

Simple.

No need to overcomplicate it.

Now for the important question: how do you cook it?

This is where things get exciting.

Because we think one of the biggest barriers to trying tempeh isn't the taste.

It's uncertainty.

People buy a block.

They take it home.

They put it in the fridge.

And then they look at it again three days later and think:

"What am I supposed to do with you?"

We've been there.

So here's our simplest starting point.

Our very simple way to cook fresh tempeh

Take your fresh tempeh.

Slice it thinly—around 1mm if you like it really crispy.

Add a little olive oil.

Add some salt.

Then add whatever spices you enjoy.

We often use mixed spice, but this is where you can make it your own.

Then either:

Pan-fry it until golden and crisp.

Or, for an easy option:

 

Air-fry at around 180°C for about 8-9 minutes, giving it a little longer if you prefer it extra crispy.

That's it.

No complicated marinade.

No twenty ingredients.

Just tempeh, seasoning and heat.

And once you've tried it that way, you can start experimenting.

Garlic.

Chilli.

Smoked paprika.

Soy sauce.

Ginger.

Curry spices.

Sesame.

Lemon.

Whatever happens to be in your kitchen.

That's one of our favourite things about tempeh.

It gives you somewhere to start.

What if I don't like it?

That's okay.

Honestly.

We don't expect everyone to fall in love with tempeh immediately.

Some people do.

Some people need to try it a couple of different ways.

And some people simply prefer something else.

That's food.

But if you've only tried tempeh once—especially if it was poorly cooked, under-seasoned or simply not to your taste—we'd say:

Try it another way before you decide.

Thin and crispy can be very different from thick and soft.

Pan-fried can be very different from steamed.

Strongly seasoned can be very different from plain.

Sometimes the difference between "I don't like tempeh" and "Oh… I actually really like this" is simply learning how to cook it.

We've seen that happen more than once.

Are black or grey spots on tempeh safe?

Another question that comes up a lot.

During tempeh fermentation, you may sometimes see grey or black areas as the culture develops and produces spores.

That can be part of normal tempeh maturation.

However, if the tempeh has an unusual smell, particularly a strong ammonia or rotten smell, or has unexpected coloured mould or other signs of spoilage, don't eat it.

When it comes to food, if something doesn't look or smell right, it's always better to be cautious.

And, as ever, follow the storage and use-by instructions for the particular product you're buying.

Can you freeze tempeh?

Yes.

Tempeh can be frozen, which is useful if you've bought more than you're going to cook immediately.

Wrap it well or keep it in a suitable sealed container and follow the producer's storage guidance.

The texture can change slightly after freezing and thawing, but it can still work beautifully in hearty dishes, stir-fries, curries and other cooked meals.

So… why are we so excited about it?

This is probably the easiest question for us to answer.

Because tempeh feels like one of those foods that has been waiting patiently for more people to discover it.

It has history.

It has character.

It has texture.

It's nutritious.

It's versatile.

And perhaps most importantly, it's fun to cook.

There's something satisfying about putting a plain little block into a hot pan and watching it transform.

Golden edges.

Crisp corners.

That nutty smell.

And then that first bite.

That's the moment we want more people to experience.

From Indonesia to Wales

There is also something quite special about where our own tempeh journey has taken us.

Tempeh has deep roots in Indonesia.

And here we are, making it in Wales.

We didn't invent tempeh.

We don't want to pretend we did.

We're simply part of a much longer story.

Our job is to learn from the tradition, make something we are proud of, and introduce it to people who may never have encountered it before.

One batch at a time.

One market at a time.

One curious customer at a time.

Maybe your first bite is next

If you're completely new to tempeh, don't worry about knowing everything.

You don't need to understand fermentation.

You don't need to know the history.

You don't need to have a cupboard full of specialist ingredients.

You just need a block of tempeh, a frying pan, a little oil, some seasoning and a bit of curiosity.

Slice it.

Cook it.

Make it crisp.

Take a bite.

And see what you think.

Because that's really how every Calon journey begins.

With a little curiosity.

And maybe, if we're lucky, with:

"Oh… that's actually really good."

We hope you'll give it a try.

If you’d rather start with a snack, try our tempeh crisps.

And if you do, we'd love to know how you cooked yours.

Because we're still learning too.

Calon.

Protein with a place.