Home-Made Indian Yogurt/Curd (Dahi)

How to make Indian-style yogurt (dahi) at home.

Indian cuisine varies a lot, but there are a few ingredients that are integral to our food, and one such item would be Dahi (Indian yogurt) - also referred quite commonly as curd all over India.  Whether served along with aloo paranthas (Indian bread stuffed with spiced potato) or used to make thair saadam (curd rice), dahi is a staple in most Indian households.  This is easily available in stores, but making home-made dahi is healthier and also has the ideal tangy taste (when allowed to ferment for longer time) that is essential for a lot of dishes.  Fortunately, making dahi is definitely no rocket science - it's easy enough for me to do at home every day!  Here's an easy guide to making Indian-style yogurt at home:

I prefer to use whole milk for making yogurt.  Generally, I find that the more the fat content in the milk, the tastier/thicker the dahi turns out to be.  I do know a lot of people who prefer using low-fat milk as a healthier alternative.  In the US, I use organic whole milk - find it the best for making yogurt at home.  In India, organic milk isn't heard of at least where I live, and I always use Nandini Good Life (should be familiar to those of you who live in Karnataka).

For making dahi, apart from the milk mentioned earlier, you also need a starter for the yogurt.  Usually, this is leftover yogurt - we make a fresh batch almost every day.  On the rare occasions that I use up all the yogurt, I have to borrow the starter from my mom :P  In the US, I buy organic yogurt - Strauss (available at Whole Foods) or the Trader Joe's Organic Yogurt.  Full fat versions of either one work great as starters. 

I use a microwave safe bowl to make/store yogurt.  It's not essential, but I find that using glass or stainless steel vessels to make and store the yogurt gives better results than using something like plastic.  Also, microwave bowls are easier to use and clean.  I use about 400 mL of milk and bring it to a boil in the microwave - keep it aside to cool down and reach a lukewarm temperature.  It's essential that the temperature reaches a barely warm level.  Using warm or hot milk to make yogurt equals disaster - it kills the microorganisms that actually ferment the milk to make the yogurt.

This step is definitely optional.  In fact, most people would roll their eyes at this :P  Skip if you wish to.  As the milk cools down, a skin forms over the surface of the milk, and I discard this.  It's just personal preference - I don't like it, and it stays on as a skin in the yogurt too, which I hate.

Once the milk has reached the ideal barely warm temperature, mix in about 2-3 tablespoons (for about 400 mL milk) of the starter/leftover yogurt to the milk.

Stir this starter yogurt into the milk gently to help it mix in properly.

Cover the bowl and set it aside, undisturbed in a not-so-lit place, until set.  The yogurt is done when the milk sets to a thick custard-like consistency all over.  Takes about 4-5 hours if you live in a really warm place - a maximum of overnight, otherwise.  Dip a spoon in the yogurt and check after about 5 hours to ensure that it has set all over and not just on the surface.  I prefer dahi to be less tangy, so I put it in the fridge soon as it has set.  If you need the dahi to be very sour/tangy, leave it outside longer.

In winters or on cooler days, it does get a bit difficult to get the yogurt to set properly.  One trick is to leave the bowl of milk-yogurt mixture in the oven with the light turned on for a bit of warmth.  I prefer to place the bowl in some warm water (in a larger container).  I do need to change the water often, as it cools down, but I find this a more reliable method to getting proper yogurt.

Dahi tastes delicious on its own, but it also can be used to make a ton of Indian recipes - will share those in a bit :)