Peel and chop the onion.

In a non-stick pan with two tablespoons of olive oil, sauté one onion, until softened.

When the onion has softened, add the peas and half cup of water, add salt and pepper.

Cook for about 10 minutes over medium heat, until the peas have turned soft.

When the peas are ready transfer them to a bowl and let them cool.

Meanwhile, in another bowl, break the eggs, add the parmesan cheese, salt and black pepper, and lightly beat them with a fork, being careful not to overbeat them.

At this point add the peas, and amalgamate them with the eggs.

In the pan where you cooked the peas, add a tablespoon of olive oil, and let it heat up. When it is hot, add the mixture and lower the heat and cover with a lid, let it cook for about 5 to 7 minutes.

Gently shaking the pan every few minutes.

At this point the part that seems most difficult, but is not if you use the right pan. Help yourself with a plate the same diameter as the pan. Place it on top and flip the omelet.

Add a little olive oil if needed, and gently  slide  the frittata on the other side.

Let it cook for another 5 minutes or so.

Flip the frittata on the plate again.

Serve with your favorite side dish