Yoghurt is a western thing, and I've included this recipe, not because it's Thai, but because it contains a common Thai ingredient: coconut milk. You see, yoghurt doesn't need to be made from milk, it can be made from coconut milk too, and if you use the coconut milk powder you can make a much thicker concentrated and creamier yoghurt by using less water than the powder was designed for.
Once you've made it, it's not healthy! Coconut milk is rich at the best of times, and a concentrated coconut yoghurt is best used sparingly as a topping for fruit, or a sauce on a desert!
The main things you'll need, a thermometer that can read 40 degrees Celsius and a live yoghurt as a starter. It must be live, with live bacteria, as the lactic acid making bacteria are the key to a yoghurt. I've used Yolida, a Thai brand. I've also made this using my rice cooker, which I found to be ideal, but a double boiler pan can also be used.
Ingredients (for a 1 1/2 Litre Glass Jar)
370 gms Coconut Cream Powder (1 Packet)
1 Litre Water
40 gms Sugar
3-4 Tablespoons Yolida Live Yoghurt
1. Put the water into the rice cooker, together with the sugar and coconut powder.
2. Turn the rice cooker onto 'cook'. As it warms up, stir the powder into the water and it will blend to form a thick sweet coconut cream. A lot of the sweetness will go as the bacteria does its work.
3. Take the temperature above 80 degrees Celsius, checking it with the thermometer every now and again. This is to ensure any competing bacteria in the water and powder are killed.
4. Cool it down, by placing the inner metal rice pan into a cold bath of water. Lower the temperature of the milk to around 40 degrees Celsius. This is the temperature, the yoghurt culture likes best.
5. Add 4-5 large tablespoons of live yoghurt and stir it in. You can add more, but this is enough.
6. Place the pot back into the rice cooker and turn the rice cooker onto warm.
7. Check the temperature, my rice cookers warm setting keeps it at around 38 which is fine for yoghurt making, if it gets too hot it will kill the yoghurt bacteria.
8. As the bacteria grows, it makes its own heat, I found that after about 1-2 hours I could turn off the warmer and it would stay in the 40-45 degree range.
9. Coconut yoghurt needs longer than milk yoghurt, I found I needed to culture it for 8 hours before it became thick enough and the sweetness reduced enough for my taste.
10. You can add more sugar at this point if you want it sweeter. Stir in sugar to dissolve it in the warm yoghurt.
11. Transfer it to a jar with a lid, and place in the fridge to cool overnight.
12. The yoghurt will separate into thick curd like yoghurt and watery whey after the night in the fridge. You can make the yoghurt thicker by draining off the whey, but its not really essential.