Ideally get 20-30 big red chillies. I used 160 small ones from my garden. Take the crown off, slit and remove the insides of the chillies. Meanwhile, coarsely grind together 3 tbsps each of mustard seeds and fenugreek seeds, and double that of fennel seeds. Add a big spoon of turmeric, salt to taste, 5 spoons of amchur (dry mango powder) and a little hing. Add enough mustard oil to this mix to just get the mix sticky, then stuff the chillies with it. Put in a glass jar, cover with mustard oil and let it sit for a week in the sun!
Delicious.