Italian omelette

Both Spain and Italy have traditional omelettes – tortilla in Spain and frittata in Italy – made with lots of eggs and cooked into a more solid, sliceable dish than a French omelette, eaten either hot or at room temperature. Tortillas are denser, using sliced potatoes, but both are fantastic vehicles for an infinite array of leftovers and ideal for picnics.

• Whisk the eggs in a bowl and add the leftovers and the salt. Leave to rest for 5 minutes.
• Heat the oil in a medium, heavy-based frying pan, then add the onion and cook, stirring, until it is just starting to colour. Pour over the egg mixture and cook over a medium heat until the base of the omelette is set and beginning to brown and the top is just a little runny. Now you need to flip the omelette over. The easiest way is to put a plate over the frying pan and invert the whole lot until the omelette is on the plate, cooked-side up. Then slide it back into the pan (raw-side down) and cook for a further couple of minutes to set the egg. Alternatively, put the pan under the grill to brown the uncooked top lightly.
• Once cooked, slide the omelette out on to a clean plate and serve hot or cold, cut into wedges.
• Lots of ideas for ingredients:
• Cold boiled potatoes Slice the potatoes and brown them gently in a little butter or oil in a frying pan. Add them to the eggs with some chopped herbs, if you have them, and a chopped garlic clove. Leftover kale or broccoli could also go in here.
• Cold boiled potatoes and cheese: Slice the potatoes and add them with some crumbled cheese while the omelette cooks. Blue cheese is particularly luscious but most other cheeses, especially goat’s cheese, also taste great with potato. Add a few thyme leaves, too.
• Ham, prosciutto or jamon serrano :These are ideal with sliced leftover boiled potatoes, prepared as above. Simply shred the meat roughly before adding to the eggs or directly to the omelette as it cooks. You could also add cooked asparagus, cooked spinach or some thinly sliced cooked fennel. Grate some Parmesan into the omelette as it begins to set.
• Bacon: Lightly fry the last couple of rashers in the fridge and roughly chop them. Add them along with some chopped parsley, sliced spring onion and a grating of Cheddar, if you like.
• Fish :Any leftover fish works well, as does flaked canned tuna or defrosted cooked prawns. Include a tablespoon of chopped tomato and a handful of chopped parsley, or try something more Scandinavian with smoked salmon and chopped dill.
• Chorizo and red onion :Use a red onion and add some diced or sliced chorizo to the eggs, plus a little fresh thyme or oregano, if you have them.