1. Mince forcemeat with onion, salt and pepper. Pour a dollop of water, fry in oil and cool.
2. Scald tomatoes, put in cold water, peel and cut into circles.
3. Cook cannelloni.
4. Fill in cannelloni with prepared stuffing, put in greased frying pan at one layer, interlaying with thin cheese slices. Scatter over tomato circles, season with the remaining grated cheese, sprinkle with oil, cover with a lid and bake for 30-40 minutes.