Grate the zucchini and then drain the excess juice. Crush the onion and garlic and fry them in a few tablespoons of oil. Add the grated zucchini and stir until the liquid evaporates.
Separately, beat the eggs with a little salt, black pepper, flour, baking soda and mustard. Pour this over the vegetables and once it stiffens, sprinkle them with a little feta cheese and grated cheese if desired.
Put a lid on for a brief moment, turn the omelette over using a plate and fold it carefully into 2. Serve the omelette with zucchini immediately, garnished with salad and sprinkled with some chopped dill / parsley.