Classic Tomato Pasta with Sautéed Onions

1.Bring a large pot of heavily salted water to a rolling boil. Add the pasta and cook according to package directions until perfectly al dente.

2.While the pasta cooks, prepare the sauce base. In a large, deep skillet or Dutch oven, melt the butter with the olive oil over medium-low heat.

3.Add the thinly sliced onions to the skillet. Sauté slowly for 15 to 20 minutes, stirring occasionally, until they are deeply golden brown, soft, and caramelized. This slow process is key to flavor.

4.Add the minced garlic and red pepper flakes (if using) to the onions and cook for 1 minute until fragrant, being careful not to burn the garlic.

5.Pour in the crushed tomatoes, dried oregano, sugar, salt, and pepper. If using whole peeled tomatoes, crush them gently with your hands before adding. Stir well to combine.

6.Bring the sauce to a gentle simmer, then reduce the heat to low, cover partially, and let it cook for at least 20 minutes, allowing the flavors to meld. Stir occasionally.

7.About 5 minutes before the pasta is done, add the torn butter lettuce directly into the simmering tomato sauce. Stir until the lettuce wilts down completely into the sauce, adding a slight fresh green note.

8.Before draining the pasta, reserve about 1 cup of the starchy cooking water.

9.Drain the al dente pasta and immediately transfer it directly into the skillet with the tomato sauce. Add 1/2 cup of the reserved pasta water.

10.Toss vigorously over medium heat for 1 to 2 minutes until the sauce emulsifies and clings beautifully to the pasta. Add more pasta water if the sauce seems too thick.

11.Taste and adjust seasoning (salt and pepper) if necessary. Serve immediately, garnished generously with fresh chopped basil and grated Parmesan cheese, if desired.