1. Blanch the tomatoes in boiling water. Drain, skin, and seed the tomatoes, then roughly chop the flesh. Chop the sausage into small pieces. (squeeze the meat out of the skins)
2. Melt the butter in a saucepan and fry the sausage until it is golden. Add the onion and garlic and fry over a medium heat until softened.
3. Add the tomatoes and oregano to the saucepan and season to taste. Lower the heat and simmer for 10 to 12 minutes.
4. Bring a pan of salted water to a boil. Add the orecchiette and oil and cook for 12 minutes, until just tender. Drain the pasta and transfer to a warm serving dish. Spoon the sausage and tomato sauce over the pasta, toss to coat, and serve with the cheese.