In a mixing bowl, mash the cooked chickpeas until slightly chunky.
Add ground oats, chopped onion, green chillies, cumin powder, coriander powder, and salt. Mix well.
Form the mixture into patties.
Heat a non-stick pan with a little oil and cook the patties until golden brown on both sides.
Toast the burger buns lightly.
Assemble the burger by spreading vegan mayonnaise on the bun, adding lettuce, the chickpea patty, sliced tomatoes, cucumbers, and garnish with coriander leaves.
Serve hot with your choice of chutney or sauce.