From: The Kitchn

Makes about a quart

What You Need:

2 (14-ounce) cans coconut milk
2 teaspoons agar agar flakes, or 2 tablespoons tapioca starch (see Recipe Notes)
4 probiotic capsules, or 4 tablespoons store-bought coconut yogurt
2 tablespoons raw sugar or maple syrup, optional
Equipment
Glass jars with lids, for storing the yogurt
Measuring spoons
Medium saucepan
Whisk
Thermometer, optional (180 degrees, 100 degrees)

Instructions:

Warm the oven and sterilize the jars: Warm the oven for about 5 minutes, until it reaches about 100°F, then turn off the heat — leave the light on to help keep the oven warm. Fill the jar(s) you’ll use for storing the yogurt with boiling water to sterilize them. Let stand a few minutes, then pour the water out. Alternatively, you can run the jars through the dishwasher.

Pour the coconut milk into a saucepan: Shake the can of coconut milk, open it, and pour it into a medium pot. Whisk until the milk is smooth and uniform.

Add the thickener: If you’re using agar agar, sprinkle 1 teaspoon of agar agar flakes into the pot over the coconut milk — but don’t stir! If you’re using tapioca starch, scoop out roughly 1/3 cup of the coconut milk and transfer to a bowl with the starch. Whisk this together until the starch is dissolved, then pour back into the pot.

Warm the coconut milk: Place the pan on the stove over medium heat and warm until the coconut milk starts to simmer. (The agar agar will also start to melt together.) Whisk the milk and turn down the heat to low. Continue cooking on low, whisking occasionally, until 180 degrees, about 5 to 10 minutes, until the agar agar flakes are fully dissolved or the tapioca starch has thickened the mixture.

Cool the milk: Cool the milk until it’s just warm to the touch, about 100°F.

Add the probiotics: Twist open the probiotic capsule and pour the powdery contents over the milk (discard the capsule’s casing). Whisk to combine. Alternatively, whisk in 4 tablespoons store-bought coconut yogurt.

Add the sugar or maple syrup. Whisk together well.

Pour into jar(s) and allow the yogurt to set for 12 to 24 hours: Pour the coconut milk into the sterilized jar(s) and screw on the lid(s). Place into the oven — turn the oven light on to keep the environment warm. Alternatively, use a yogurt maker or place into a dehydrator at 110°F. Leave for 12 to 24 hours without disturbing.

Chill the yogurt: Place the set yogurt into the fridge and chill for at least 6 hours. The yogurt will become thicker as it chills. After this stage, you might find that the mixture has separated with a yellowish, translucent layer at the bottom and a thicker white layer on top. Stir to recombine or scoop off the top layer for thicker coconut yogurt.

Keep coconut yogurt refrigerated and use within 2 weeks.