Take your milk in a sauce pan or in a microwave safe bowl. Boil it. If you are using microwave, boil it for 6 to 7 mins. Keep an eye over the milk.
Remove this from the pan and pour it into another bowl and allow it to come to luke warm temperature.
Now take a clean container. Add your curd in that and beat it till it gets creamy and smooth.
Now pour over the luke warm milk and whisk it till combined. You should mix this very good. You can use a hand blender to mix it well.
Cover the container with a lid and leave it in a warm place(in my house everywhere is warm, so i leave it over the counter top) for around 6 to 8 hours, it even takes 10 hours.
Once it has had it time. Place them in the fridge for a good couple of hours.
Now your yogurt is done.
You can serve as it is or add some sugar and serve as lassi.
How fresh curd can be consumed:
Add some sugar into the thick curd and beat it well, have it as lassi. Add some salt, ginger & chilli juice, water and beat it well till it forms a liquid. This is what we call as sambaram.
Try to use a good starter to make your first batch of curd. It can be storebought or it can be from your previous batch of curd. The starter should be at room temperature.
If you want thick, creamy curd just like mine, Use a full fat milk. I always use "Arokya milk" when i make curd. If you use skimmed or low fat milk then the curd will not set thick, It will be runny.
The temperature of the milk should be luke warm, just as the water which you add yeast in while making bread. If you add starter curd to hot milk, then the milk will curdle. If you add starter curd to cold milk, then the curd wont set.So make sure your milk is warm when you add the starter curd in. Another way to find the temperature of the milk is. If you dip your finger into the milk, it should be like a very warm bath, if it is too hot then you should allow the milk to cool completely.If you live in cold place then, you want to leave the container in a warm oven for 8 to 10 hours. Turn the oven light on, so that it creates a warm temperature inside the oven.
You can use stainless steel utensil, air tight plastic containers, tupperware, glass containers.