Prep the vegetables: Dice the bell peppers, onions, and tomatoes into small, even pieces for even cooking.

Whisk the eggs: In a bowl, beat the eggs with milk, a pinch of salt, and pepper until well combined and slightly frothy.

Cook the vegetables: Heat butter in a non-stick pan over medium heat. Add the diced onions and bell peppers, sauté for 1-2 minutes until slightly softened.

Add tomatoes: Stir in the diced tomatoes and cook for another 30 seconds. Spread the vegetables evenly in the pan.

Pour the eggs: Pour the whisked eggs over the vegetables. Let it sit for a few seconds until the edges start to set.

Cook the omelette: Gently lift the edges with a spatula to let the uncooked egg flow underneath. Sprinkle cheese on top.

Fold and serve: Once the omelette is mostly set but still slightly runny on top, fold it in half. Cook for another 30 seconds, then slide onto a plate. Garnish with fresh herbs if desired.