Combine the nuts, rice, and 2 cups of water in a large mixing bowl. Allow for a total of 2 1/2 hours of soak time. Drain. Add 2 cups of freshwater to the solids in a blender. Blend until smooth and covered. Using a fine-mesh sieve, strain the milk mixture.
In a medium pot, pour the milk mixture. 2 cups of fresh water and agar powder. Bring to a boil, then turn off the heat. Cook, occasionally stirring, for about 10 minutes, or until the agar has dissolved, uncovered. Remove the pan from the heat. Allow cooling to 110 degrees Fahrenheit. (This is critical.) The living microorganisms in the yoghurt starter will be killed at a higher temperature.) Add the yoghurt starter and mix well.
Cover two 16-ounce jars or other glass containers with tight-fitting lids with the liquid.
Place jars in a warm, dry place for 8 hours, such as in the oven with the light on or near the stove.
Yoghurt should be stirred or shaken. Refrigerate for at least 6 hours or until thickened, stirring once or twice. Keep refrigerated for up to 2 weeks.