Peel and grate potatoes. Put grated potatoes into a bowl, add cornstarch and salt. Mix well. Divide mixture into 12 equal portions and roll into balls. Set aside. Heat oil in nonstick pan, add cumin and stir until they begin to crackle. Add peas and cook stirring occasionally until peas are cooked. Add coriander and cayenne. Cook and stir for 1 minute. Remove from heat and mash mixture. Flatten each potato ball in the palm of your hand. Place 12 of the pea mixture into the middle, Reform the balls and then flatten them into a 3/4 inch patty. Mist a heated skillet lightly with olive oil spray. Cook patties over moderate heat until crisp and golden on both sides. Press with spatula and remove.