Put the chopped chillies and ginger in a mortar or strong bowl and crush to a paste with a pestle or the end of a rolling pin. Put the oil, water, bicarbonate of soda, and the ginger and chilli paste in a saucepan. Add salt and asafoetida powder to taste, stir well and heat. When hot, add the peas and cook for 10 minutes. (The peas should not change their colour) Remove from the heat and serve, garnished with coriander and coconut. (if using)