Preparation Heat 1 tablespoon oil in heavy large skillet over medium heat. Add half of guanciale and sauté until crisp, about 5 minutes. Transfer guanciale to paper towels to drain (do not clean skillet). Reserve for garnish. Add 2 tablespoons oil to same skillet over medium-low heat. Add garlic and peperoncino; sauté until peperoncino darkens, about 2 minutes. Add onion and remaining guanciale; sauté until onion is translucent and fat has rendered from guanciale, about 10 minutes. Stir in vinegar; cook 1 minute. Add tomatoes; simmer 6 minutes. Season sauce with salt and pepper. Meanwhile, cook pasta in large pot of boiling salted water until just tender but still firm to bite. Drain, reserving 1/2 cup pasta cooking liquid. Return pasta to same pot. Add tomato sauce and cheese to pasta and toss, adding some of reserved pasta cooking liquid if dry. Season to taste with salt and pepper. Transfer pasta to bowl. Sprinkle with reserved guanciale and serve.
Preparation Heat 1 tablespoon oil in heavy large skillet over medium heat. Add half of guanciale and sauté until crisp, about 5 minutes. Transfer guanciale to paper towels to drain (do not clean skillet). Reserve for garnish. Add 2 tablespoons oil to same skillet over medium-low heat. Add garlic and peperoncino; sauté until peperoncino darkens, about 2 minutes. Add onion and remaining guanciale; sauté until onion is translucent and fat has rendered from guanciale, about 10 minutes. Stir in vinegar; cook 1 minute. Add tomatoes; simmer 6 minutes. Season sauce with salt and pepper. Meanwhile, cook pasta in large pot of boiling salted water until just tender but still firm to bite. Drain, reserving 1/2 cup pasta cooking liquid. Return pasta to same pot. Add tomato sauce and cheese to pasta and toss, adding some of reserved pasta cooking liquid if dry. Season to taste with salt and pepper. Transfer pasta to bowl. Sprinkle with reserved guanciale and serve.