You could make this with spaghetti or linguine or other types of long skinny pasta, but bucatini are what’s used in Rome. Tasty, salty, savory guanciale, made from cured pork cheeks, has become more available in North America in recent years, but if you can’t find it, substitute a good lean pancetta. And if that’s not available, use slab bacon but blanch it for 3 to 4 minutes in boiling water to rid it of its smoky aroma.
In a saucepan over medium heat, gently saute the garlic, onion, and guanciale in the oil, stirring occasionally, until the meat renders a little fat and the vegetables just begin to brown-about 15 to 20 minutes. Add the tomatoes and stir to mix. Cook the tomatoes for about 5 minutes, and when they start to give off their juice, lower the heat and simmer, stirring occasionally, until the sauce is dense, about 20 minutes. Add salt and pepper. Meanwhile, cook the pasta in lightly salted water according to the directions on page 193. Drain it, turn it into a warmed serving bowl, and pour the sauce over it. Serve immediately, passing the grated cheese.