Cut the leeks into rings, grate the carrots.
Heat the oil, sauté the vegetables and mix with drained soybean germ.
For the sauce, heat the fat again, sweat the flour in it and deglaze with water. Add strained tomatoes and spices, bring to a boil and season.
Drain the tuna and cut into pieces. Chop the cucumbers and mix with a quarter of the sauce.
In a greased rectangular gratin dish, alternate layers of lasagna sheets, vegetables and tuna.
Finish with pasta and spread remaining sauce over the top.
Sprinkle with cheese and place the dish in the cold oven.
Bake the lasagna at 200 °C for 35-45 minutes.