Preheat oven (electric cooker: 225 °C/circulating air: 200 °C/gas: see manufacturer). Rinse beans in a sieve with cold water and drain. Peel the skin off the sausage, cut the sausage into slices. Peel and chop onions.
Heat the oil in a frying pan. Fry the chorizo in it. Fry the onions briefly. Add beans, frozen peas and tomatoes and bring to the boil. Mix in uncooked tortelloni. Season with salt and pepper.
Pour into a greased casserole dish. Grate the cheese directly over it. Bake in a hot oven for about 15 minutes.