Rinse the yellow split peas and cover with cold water in a bowl. Allow to soak overnight.
Drain the peas and pulse into a coarse paste in a food processor.
Add the rest of the ingredients- finely chopped onions, cumin seeds, fennel seeds, chopped coriander and chopped chives, salt and chilli (if using).
Mix thoroughly and press small scoops of the mixture in your hands to form small balls.
Heat the vegetable oil into a deep, heavy-based saucepan. When the oil is hot, carefully drop one the balls in. It should sizzle vigorously but not brown too quickly. The gateaux piments should take a couple to minutes to get brown and crunchy.
Fry 4-8 balls at a time depending on the size of your saucepan.
Remove from the oil using a slotted spoon and drain for a couple of minutes on a piece of kitchen paper.
Eat when hot with some spicy salsa or if you are seeking the authentic Mauritian experience, in a buttered baguette.