- Take a pan and add 2tbsp of oil,cumin, mustard,saute well and then add garam masala, coriander powder,cumin powder,salt,ginger garlic paste,green chillies,onion saute well for 3-4 minutes.then add the mashed potato and mix well. Keep this aside and Place 2 bread slices in pan and drizzle butter let it turn brown in colour. Then place the prepared potato stuff on one bread and cover it off with another bread slice then garnish the top with coriander and serve hot.