Vegetarian Lasagna

Preheat the oven to 180°C (approximately 350°F). For the tomato sauce, peel onion and garlic and chop finely. Add 4 tablespoons olive oil to a saucepan and sauté onion and garlic. Add the tomatoes and 4 teaspoon sugar and bring to a boil over high heat. Let the sauce boil for about 2 minutes while stirring. Reduce heat and simmer, covered for another 5 minutes. Season with chilli powder, salt and pepper.

For the vegetables, rinse the celery and cut into 1 cm (approximately 1/2 inch) thick pieces. Rinse and cut the broccoli into florets. Peel the stems and cut into small cubes. Bring salted water to a boil and blanch the vegetables in it for 5 minutes, then drain. Rinse and cut the scallions into thin rings.

For assembling, grease a baking dish with butter and line with lasagna sheets. Cover with sauce. Top with the vegetables and the basil leaves. Continue layering with sauce and remaining vegetables. Finish with more sauce.