How to Make Thick Yogurt (Dahi) at Home

Why make your own

Homemade dahi is thicker, creamier and milder than most shop yogurt, it costs only the price of the milk, and it’s the way most South Asian households have always made it. You need just two things: milk and a spoonful of live yogurt (jaag or jamun) to start it. Good yogurt makes better raita, lassi, marinades and qormas.

How it works

Live yogurt contains friendly bacteria. When you add a little to warm milk, they multiply, feeding on the milk sugar (lactose) and producing lactic acid. The acid makes the milk proteins set into a soft gel, and gives yogurt its tang. The bacteria work best at body warmth, about 40–45°C. Too hot and they die; too cold and they barely work.

Method

You’ll need: 1 litre full-fat milk and 1–2 tablespoons of plain yogurt with live cultures (from your last batch or a plain, unflavoured shop yogurt).

1. Boil the milk, then simmer for 3–5 minutes. This thickens it a little and makes firmer yogurt. For extra-thick dahi, simmer for 10 minutes until reduced by about a tenth.
2. Cool to lukewarm, about 40–45°C. Test with a clean finger: you should be able to hold it in the milk for 10 seconds comfortably. It should feel warm, not hot.
3. Mix the starter: whisk the yogurt in a bowl with a few spoons of the warm milk until smooth, then stir it into the rest.
4. Pour into a clay pot, ceramic or steel bowl. Clay absorbs some water and gives the thickest result.
5. Cover and leave undisturbed in a warm place for 5–8 hours in summer, or 8–12 hours in winter. Don’t move or stir it while it sets.
6. Check: it’s ready when it holds together and pulls away cleanly from the side when you tilt the bowl.
7. Chill for at least 2 hours. It firms up more in the fridge and stops getting sourer.

Keep 2 tablespoons aside as the starter for your next batch.

Setting yogurt in winter

Cold kitchens are the main reason yogurt fails. Try one of these:

• Put the bowl in an oven with just the light on.
• Wrap the bowl in a thick towel or blanket and put it in a box or cupboard.
• Put it near (not on) a heater or on top of the fridge.
• Use the yogurt setting on an Instant Pot.
• Use slightly warmer milk (about 45°C) and a little more starter.

Problems and fixes

• Runny or didn’t set: the milk was too hot (killing the bacteria) or too cold, or the starter was weak. Use a fresh plain yogurt as starter and check the temperature.
• Too sour: it was left too long or somewhere too warm. Chill it as soon as it sets. Use sour yogurt in kadhi or marinades.
• Watery layer on top: that’s whey; it’s normal. Stir it back in, or pour it off for thicker yogurt.
• Slimy or stringy: the starter was contaminated. Start again with fresh yogurt.

Thicker still

For Greek-style yogurt, labneh or shrikhand, hang the set yogurt in a cloth over a bowl in the fridge for 2–12 hours. The longer it hangs, the thicker it gets. Use the drained whey in roti dough or smoothies.

For using yogurt in cooking without splitting, see our guide to cooking with yogurt.