Any of the following vegan curd starters:
Drain the cashew nuts and grind them with 2-3 tbsp water to a fine paste and keep aside. Take 100 ml water in a pan and add the agar agar to it. Boil this mixture, stirring frequently, until the agar agar dissolves. Add the cashew paste to this boiling water and mix well. Immediately add the balance water to it and keep stirring for 5 minutes. As it boils, it will thicken more.
When thick, remove the mixture from the heat and keep stirring until it cools down to a lukewarm temperature (37 °C/ 98 °F). Add the starter to it and keep to set at room temperature for about 6-8 hours, depending on the climate. It may take more time to set in cooler places.
This yoghurt keeps for 4 to 5 days in the refrigerator.
Set the yoghurt in a glass or earthen pot for best results. Keep the lid slightly open or cover with a cloth.
If you wish to reduce the amount of nuts, you may substitute half the quantity of nuts with melon seeds and use cashew nuts and melon seeds in the ratio 1:1.
Try making a small amount first, since yoghurt can be a bit unpredictable the first few times. With the chilli tops, you may need to reserve some of the batch and use again with a fresh batch and more chilli tops, until you get a firm set yoghurt, which can be used as a starter for further batches. A starter portion of yoghurt or a starter culture normally gives reliable results.