In a frying pan, fry the chopped onion and pepper, adding the tuna and the tomato sauce to create the lasagna filling. Season with salt and pepper and let cool before starting to assemble the lasagna.
We place the lasagna sheets to soak so they soften. Then we put them in a baking dish, with a layer of bechamel sauce underneath so it doesn’t stick. We can buy it made or follow this delicious homemade bechamel recipe.
We begin to build, a sheet of lasagna and a layer of filling. When we get to the end, cover with bechamel sauce, put it in the oven for 15 minutes at 190ºC, sprinkle with cheese and gratin until golden brown.