Bring a large pot of water to a boil for the pasta. Add a little salt.
Meanwhile, heat the oil in a nonreactive large nonstick skillet over medium-high heat. Add the onion, red and yellow bell peppers, pepper flakes, and a sprinkling of salt. Cover and sweat (or cook) for 3 minutes. Uncover and cook, tossing with a wooden spoon, until the vegetables are crisp-t