Preheat the oven to 180°C and grease a baking tray.
Blend the ginger and green chillies into a paste using a food processor.
Pulse the peas in the food processor and set aside.
Fry mustard seeds in oil in a lidded pan until they pop.
Stir-fry the chilli-ginger paste for 2 minutes and add the pea purée.
Add spices and salt, cooking until moisture evaporates while maintaining green color.
Rub flour, salt, and oil together until the mixture resembles breadcrumbs.
Knead in 175ml of hot water to form a firm, oiled dough ball.
Roll apricot-sized dough pieces into 10cm circles on a floured surface.
Place 5ml of filling in each circle, seal edges, and roll into balls.
Coat the kachoris in oil on the tray and bake for 30 minutes until golden.