In a bowl add yogurt,tomato,cucumber,salt,coriander,green chili ,pepper powder and mix it well.

Take a bread slice and spread 1/2 mixture over it.

Cover it with another bread slice to make a sandwich.

On a heavy griddle or a non stick tawa spread 1 tsp oil and sprinkle mustard seeds and chopped curry leaves

When mustard seeds start to crackle then place the sandwich over this tempering and cook on slow flame.

When it become golden then spread little oil or ghee on the top slice.

Turn the sandwich and cook from other side by gently pressing with a spatula.

When become golden from both sides remove from the griddle.

Slice it to make two pieces.

Serve hot with ketchup or chutney