Preheat oven to 190 °C and grease a 22 x 30 cm ovenproof dish with margarine.
Place the brinjal slices in a colander and sprinkle liberally with salt.
Stand for 30 minutes, rinse under cold water and pat dry.
Fry the slices in a little hot olive oil until done.
Remove from pan and drain on paper towels.
Mix the green beans and ricotta and season well with salt, black pepper, garlic and nutmeg.
Fill the cannelloni tubes with the mixture and arrange in layers in the ovenproof dish, alternating them with the brinjal slices.
Whisk the evaporated milk and cornflour together and stir in the tomatoes, sugar and parsley or basil.
Pour over the cannelloni tubes and sprinkle with Parmesan cheese.
Bake for 45 minutes or until cooked through but still firm.
Instead of beans, use baby marrows or patty pans, stir-fried with mushrooms. Mix with the ricotta and add sun-dried tomato paste for extra flavour.
Use lasagne sheets instead of cannelloni tubes. Soak them in boiling water to make them pliable and roll them up with the filling.