Heat a pan with olive oil, then sauté onions until soft. Add tomatoes and ham, and continue to stir-fry.

Mix eggs with milk and season with salt, then whisk thoroughly.

Heat a pan on low heat, add olive oil, and pour in the egg mixture. Stir gently with chopsticks to create a thick, fluffy texture.

When the eggs are half-cooked, place a slice of cheese on one side of the omelette.

Add the sautéed tomatoes and vegetables on top of the cheese.

Fold the omelette in half to cover the filling.