This classic sauce takes its spiciness from dried chiles and its depth of flavor from guanciale, Italian salt-cured pork jowl. If you can't find it, use pancetta, which is available at better supermarkets!
Thinly slice the onion with the bacon and put it in a pan with two tablespoons of olive oil. When browned, add the tomatoes to the pan, chopped seedless;
Season with salt and plenty of pepper; continue to cook on high heat for some minutes, until the mixture is cooked but not mushy;
Cook the pasta in plenty of lightly salted water and when they are cooked in the right time, drain and mix with the sauce and pecorino romano. Buon appetito!