Sort the spinach, wash and drain. Wash and halve the tomatoes. Peel and halve the onion and cut into fine strips. Mix vinegar, salt, pepper and sugar, fold in 2 tablespoons of oil. Mix the prepared ingredients with the vinaigrette.
Whisk eggs and milk, season with salt and pepper. Heat 1 tablespoon of oil in a coated frying pan. Fry half the egg mixture in it over a low to medium heat for about 5 minutes. Remove the omelette from the pan, keep warm and bake another omelette in the same way. Fill with the salad and cover with salmon.