- Finely dice the onion, mash the garlic. Heat the oil in a pan and fry the onions and garlic in it. Add the spinach, pour in the water and steam everything for about 2 minutes.
- Mix the ricotta and lemon juice and fold into the spinach. Season to taste with salt, pepper and nutmeg. Fold in the crabs.
- Briefly pre-cook the cannelloni in salted water, but not so long that they become soft. Fill with the mixture and place in a baking dish.
- Mix the tomatoes with the vinegar and the oregano leaves and season with salt and pepper. Pour over the cannelloni and sprinkle the casserole with cheese.
- Bake at 200 ° C for about 25 minutes.