Start by cleaning an onion and cutting and slicing it.

Remove the ends of the zucchini and wash them.
Slice the zucchini into thin rounds.

In a large bottomed pan, pour in 2 tablespoons of olive oil.

Add the sliced onion and sauté for a couple of minutes to soften. Season with salt and pepper to taste.

Turn up the heat, add the sliced zucchini and saute for a couple of minutes, stirring often.

In a couple of minutes the zucchini will be soft. Remove from heat.

In a bowl, beat the eggs and add salt, pepper and grated cheese.

Add the zucchini and one fresh tomato, previously diced, to the eggs mix.

Take a non-stick pan and pour in a tablespoon of olive oil. Grease both the bottom of the pan and the edges well. As soon as the pan is hot, add the eggs with the zucchini.

Level the frittata with a spoon, lower the heat and let it cook with the lid on.

After a couple of minutes, use a thin blade to pull the edge of the frittata away from the pan. Shake the pan by the handle to get the bottom to come off as well.

When the omelette is cooked on one side (about 4-5 minutes), take a large plate (it should be slightly larger than the pan you are using) and place it on top of the pan, and with a quick motion flip the frittata over.

Slide the frittata back into the pan, add another tablespoon of oil if needed.

Let the other side of the omelet cook for about 3-4 minutes.

Again with the help of a plate, with a quick movement flip the frittata in the plate.

Let the frittata rest for a couple of minutes before serving it.