In a bowl beat 4 eggs with a pinch of salt and pepper.
Heat oil in a non-stick pan.
Fry chopped onion until soft, followed by chopped tomato, chopped green chili, red chili powder, turmeric powder, salt, and black pepper powder. Fry for 2 minutes.
Add chopped mushroom and fry until well cooked. Then add whisked egg mixture and cook on low flame and keep stirring till all the eggs get scrambled and well combined with rest of the spices.
Finally, add chopped coriander leaves and mix well. This will take about 3 to 4 minutes. Remove from heat and set aside to cool down.
Take 2 slices of bread and spread mayonnaise evenly. Place a tablespoon of cooked egg and mushroom mixture and a slice of cheese. Place the other slice of bread on top and grill on a non-stick pan with some butter till golden and crispy on both sides.
Serve hot.