Whisk eggs and salt in a bowl until bubbly.

Add chopped green chilies, tomato, onion, black pepper powder, and garam masala powder to the egg mixture and whisk again.

Heat mustard oil in a skillet or flat surface pan, ensuring the pan is evenly coated.

Pour the whisked egg onto the heated pan and spread evenly.

Cook for a couple of minutes, then flip and cook the other side until golden brown.

Transfer the omelette to a chopping board and slice into 4 equal pieces.

Stuff 2 omelette slices between two pieces of bread.

Apply melted butter to the outer surface of the sandwich.

Grill on a griddle or grill pan from both sides until crispy and golden.

Serve immediately.