In a large skillet, add 1 tablespoon of the oil and sauté onion for 3 to 5 minutes. Add the optional green chili and sauté for 1 additional minute. Add mashed peas and cook for 2 minutes. Remove from heat. Stir in mashed potatoes, fresh bread crumbs, mango powder, coriander powder, salt, red chili powder, cilantro, and cornstarch. Let cool.
Form into round cutlets. Refrigerate at least 30 minutes to firm.
On medium-hot heat, skillet-fry in remaining 2 tablespoons vegetable oil until browned on both sides. Serve with chutney or ketchup.