Heat oil in large pot over medium low heat. Add onion & cook till it turns brown, stirring occasionally. Stir in potatoes & cook till they begin to brown. Stir frequently. Add cayenne, lemon, salt & turmeric. Cook for 2 to 3 minutes. Add cauliflower & chilies & stir well. Add about 1/4 c water. Continue to cook till the vegetables are tender, adding more water if necessary. Adapted from Ismail Merchant, "Indian Cuisine"