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Pour the milk into the pot and set the burner to medium low heat. Do not make the milk too hot. Let it become lukewarm. Check the milk with your finger to make sure it is lukewarm. If the milk is too hot when you add the yogurt, it will be watery and not set. Once the milk becomes lukewarm, add the curd and mix it in well with a spoon or a whisk. Alternatively, you can pour milk from one container to another 2-3 times so the curd mixes well with the milk. Don't let the dahi set in the pot you cooked it in. The heat of the pot will not allow the dahi to set. Choose a glass container or a metal container with an airtight lid. You can also set the curd in individual cups. By your oven or on your kitchen counter are good places for the dahi to set. If you live in a warmer place, the dahi will likely set within 5-6 hours. If you live in a colder place,you can set the dahi in a casserole dish and add more starter yogurt, about 1 tablespoon. Then, you can cover the container with a thick towel or cloth. You can also preheat the oven to 180 degrees C for two minutes. Then, switch off the oven and keep the dahi in the oven for 6-7 hours or overnight. If the curd does not set after 6-8 hours, or overnight, you likely used too little starter yogurt, the milk was not warm enough, or the temperature was not warm enough. So adjust these in your next batch of dahi. It will become firm after 2-3 hours. If you leave the dahi out longer than 8 hours to set (unless you live in a cold climate) and do not refrigerate it, it will become sour. If your curd comes out stringy and gooey, the temperature of the milk was likely too hot or too cold. So adjust the temperature to lukewarm for your next batch of dahi. To avoid the dahi from getting watery or "breaking", always level off the dahi if you break it and take a piece of it. Don't let the dahi sit with a slanted top. Dahi tastes great with simple ingredients like cut up fruit and nuts in the morning, as well as an additive to Indian curries.
Place a small round pot on the stove. Warm the milk. Add 1 teaspoons yogurt. Transfer the dahi to a container with a lid. Let the covered dahi set in a warm place for 7-8 hours. Refrigerate the dahi. Enjoy the dahi in a curry, a lassi, or on its own.