Lasagna the next day: with the remains of the roast

Preparation

1. Cook the lasagna sheets in plenty of salted water and a dash of oil for 8 minutes. If they are precooked plates, soak them for 10 minutes. Refresh and reserve.

2. Cut the onion into thin julienne strips and fry it in a frying pan with the previously chopped and seasoned lamb (if we use the remains of a roast, we will add them last, when the sauce is ready).

3. Once the onion is tender and the lamb is golden, add the diced zucchini and the pine nuts. Cook over medium heat for 5 minutes; add the peeled and chopped tomatoes with a pinch of salt; continue cooking another 5-6 minutes.

4. After that time, we would add the lamb in case it was leftovers from the day before, we would check the salt point and we would keep it on the fire for a few minutes to impregnate the flavor of the stir-fry.

5. On the other hand we make the béchamel: we sauté 2 tablespoons of flour in a casserole with some oil. When it has toasted, add it little by little and without stopping stirring half a liter of cold milk and a few thyme leaves and let it thicken over medium heat. Add the grated cheese when the béchamel has the desired consistency and keep on the heat until it melts.

6. Place four sheets of pasta on an oven tray 4 and assemble a layer of sauce on top of them. Add a second layer of plates, and fry, cover with the pasta, cover the lasagna with the cheese béchamel and sprinkle a little grated cheese on top. Bake at 180º or 190º until the bechamel is gratin.