Wash 150g of potatoes and chop into 1cm dice, then put into a 25cm non-stick frying pan on a medium heat with 1 tablespoon of oil and a good splash of water and toss well.
Peel 1 red onion, deseed 1 red and 1 yellow pepper, chop both into 1cm dice as well, then toss into the pan. Cook gently for 15 minutes on a medium-low heat, or until softened and lightly golden, adding splashes of water if needed, and tossing regularly.
Meanwhile, beat 4 eggs with a pinch of sea salt and black pepper for 2 minutes so they’re light and fluffy.
Toss 1 handful of frozen peas into the pan, then pour in the egg mixture. Use a rubber spatula to thoroughly mix it all together and begin to cook the eggs, then push it out flat, cover with a lid and leave to cook through for 5 minutes, or until set on the top and golden on the bottom.
While that cooks, halve 2 large ripe tomatoes and remove the cores, deseed ½–1 chilli (to your taste), place both in a blender with half the juice from 1 lemon and blitz until smooth, then taste and season to perfection.
Loosen around the edge of the omelette with the spatula, then place a large plate or board over the pan and in one bold, careful movement, flip it over onto the plate or board.
Dress 2 handfuls of rocket with the remaining lemon juice, pile in the centre, and finely grate over 15g of Parmesan. Serve the omelette warm with the salsa, and a shake of Tabasco chipotle sauce is nice too.