After the beans are cooked, drain the excess water, return to heat and add salt

Fry onions in a separate sufuria and add them to the beans, stir to mix

Add the thin coconut milk, cardamon and sugar and stir well. Allow to simmer until it's reduced, about 3/4way

Add the chilli, heavy coconut milk, curry powder and adjust salt. Allow to simmer, stirring regularly until it is thickened. Serve hot with accompaniment of choice