This Italian classic is great for weeknight dinners with the quick-cooked tomato-based sauce flavored by the rendered fat of the guanciale, sauteed onions, black pepper, red pepper and pecorino romano.
Heat a large sauté pan over medium-low heat, add the olive oil and heat through. Add the guanciale and fry until the fat renders and the lardons are crispy, about 10 minutes. Remove with a slotted spoon, reserving as much fat in the pan.
Return the pan to medium heat, add the onion and sauté until 6 minutes. Add the wine and cook, scraping any browned bits off the bottom, until the wine has almost completely evaporated, about 6 minutes.
Drain and roughly chop the tomatoes then add to the pan and bring to a simmer. Stir in the cooked guanciale, black pepper and red pepper flakes.
Bring a large pot of water to the boil; add the salt and bring back to the boil. Add the bucatini and cook, stirring occasionally, until just al dente, about 7 minutes. Set aside 1½ cups of the pasta water then drain.
Add the pasta to the pan, using tongs to toss to combine with ½ cup of the pasta water. Heat over high heat and toss the pasta rapidly until the sauce thickens and coats the noodles, adding more pasta water if the sauce gets too thick.
Remove from the heat then slowly add the pecorino, continuing to toss the pasta to combine. Season to taste with salt and serve immediately topped with additional cheese.