In a large, heavy-bottomed pot, sauté the chopped onion, celery, and carrot in 4 tablespoons of olive oil and a pat of butter.

When the vegetables are softened, add the ground meat and crumbled sausage. Cook until browned, then pour in the wine and let it evaporate.

Add the tomatoes and beef tendons. Bring to a boil, then lower the heat, cover, and let simmer gently for 2 to 3 hours. Near the end of cooking, season with salt and pepper to taste.

Meanwhile, make the pasta dough. On a work surface, mound the flour and semolina, make a well in the center, and crack in the eggs with a pinch of salt. Beat the eggs with a fork, gradually incorporating the flour until the dough comes together and is easy to work by hand.

Knead the dough for at least 10 minutes until smooth. Shape into a ball, cover with a bowl or clean towel, and let rest for 30 minutes.

Prepare the béchamel sauce: Melt the butter in a small saucepan over low heat. Add the flour and stir, then slowly pour in the warm milk, whisking to dissolve the butter and flour. Cook over low heat, stirring, until thickened. Season with salt and a pinch of nutmeg.

Bring a large pot of lightly salted water to a boil.

Roll out the pasta dough with a rolling pin or pasta machine until thin, then cut into rectangles about 4x6 inches (10x15 cm).

Cook the pasta rectangles in the boiling water, then drain and lay them out on a clean towel.

Take a 9x13 inch baking dish and assemble the lasagna: Spread a little meat sauce on the bottom, then a layer of pasta, more sauce, chopped mozzarella, Parmesan, and a few spoonfuls of béchamel. Repeat the layers until all ingredients are used.

Finish the top layer with sauce and Parmesan. Bake at 400°F (200°C) for 30 minutes.

Remove from the oven and let cool slightly, then cut and serve warm.