1 onion, finely chopped
2 teaspoons minced garlic
2 zucchini (courgette), grated
400 g sweet potato (kumera), grated
150 g button mushrooms, chopped
825 g can chopped tomatoes
3 tablespoons tomato paste
2 teaspoons sugar
salt and freshly ground black pepper or mixed herbs, to taste
spray canola or olive oil
375 g fresh lasagne sheets
500 g low-fat ricotta cheese
1/2 cup grated Parmesan cheese

Preheat the oven to moderate (180°C or 350°F).  Spray a large pan with oil and heat.  Add the onion and cook over medium heat for 3 minutes or until soft. Add the garlic and cook for 1 minute more.  Add the zucchini (courgette), sweet potato (kumera), mushrooms, tomatoes and tomato paste.  Bring to the boil, then reduce heat and simmer for 5 minutes.  Stir in the sugar, and season to taste.  Spray the base of a large lasagne dish lightly with oil.  Cut the lasagne sheets to size and arrange a layer of sheets over the base of the dish.  Top with a thin layer of sauce, then continue layering pasta and sauce, making one of the layers with the low-fat ricotta.  Finish with a thin layer of sauce on top, sprinkle with parmesan and bake for 30 minutes.  Stand for 5 minutes before cutting into squares to serve.