Ingredients:
2 tablespoonsextra-virgin olive oil
8 ouncesground mild Italian pork sausage
1 medium red onion, halved through the root end and thinly sliced
4 cloves garlic, thinly sliced
Kosher salt
Freshly ground black pepper
1 poundlong or short pasta (I used rigatoni)
3 to 5 cupsunsalted chicken or vegetable stock (or water), divided
1 (10- to 12-ounce) bag frozen peas
2 tablespoonsfreshly squeezed lemon juice (or red wine vinegar)
1/4 cupgrated parmesan, plus more for serving
Red pepper flakes, for serving (optional)
Directions:
Heat the oil in a large pot over medium-high. When the oil is shimmering, add the ground sausage and use a wooden spoon to break it up into smaller pieces. Let the sausage cook for 1 minute, then stir to break up any remaining chunks of meat. Cook undisturbed for 1 minute longer. Add the onion and garlic, then season with a big pinch of salt and lots of black pepper. Repeat, breaking up the ground sausage and tossing until the sausage is browned and nearly cooked through, and the alliums are tender and charred in spots, about 5 minutes total.
Stir in the pasta, 4 cups of stock, and 2 teaspoons of salt. Increase the heat to high and bring the mixture to a boil, stirring often, about 4 minutes. Once boiling, stir in the peas. Continue cooking the pasta, stirring often, until al dente (between 7 to 11 minutes depending on the pasta shape and strength of your burner). If the pot seems to be dry, add additional stock or water 1/4 cup at a time, letting the pasta absorb it before adding more.
Once the pasta is cooked, turn off the heat and stir in the parmesan and lemon juice. Serve immediately, with more parmesan, black pepper, and red pepper flakes if desired.