Heat 1/4 teaspoon oil in a non-stick, 26 cm pan. Add garlic, diced tomatoes, 1 pinch each of salt and pepper and cook for 5 minutes, stirring, until the liquid has largely evaporated. Remove from heat and stir in parsley. For the omelette, put the egg, egg white and 1 pinch of salt and pepper each with 2 tablespoons of water in a bowl and beat with a fork.
Heat 1 teaspoon of oil in a 26 cm pan and pour in the egg mixture. Once the omelette is firm to the bottom, move and shake the pan so that nothing sticks.
Pour the filling on the omelette, fold the omelette with a wooden spatula and serve.