Heat the oil in a wide straight-sided sauté pan or Dutch oven over medium-high heat until shimmering. Add the pancetta and cook, stirring occasoinally, until it's well-browned and the fat has mostly rendered off, a few minutes. Add the meat, season lightly with salt and pepper, and cook, breaking it up with a spoon, until it's pretty well-browned as well, 7 minutes or so.

Add the onion, celery, carrot, and garlic and cook, stirring, until the vegetables are softened but not browned, about 5 minutes. Add the minced parsley and/or sage (or the bundle of rosemary or thyme) and the tomato paste and cook, stirring, until fragrant. There should be a large amount of browned solids on the bottom of the pan by now.

Add the wine and cook, scraping up the browned bits with a wooden spoon. Continue cooking until sauce is thick and the wine has fully reduced. Add the stock and milk and stir to combine.

Bring to a boil, then reduce heat until the sauce is at the barest simmer. Cook, stirring now and then, until the sauce is rich and thick and emulsified. Fat may break out as it cooks and form a reddish slick on top. This is OK, just keep cooking and that fat will eventually get re-emulsified into the sauce.

To serve, cook up some good fresh pasta (tagliatelle is traditional) or a hearty bronze-cut dry pasta such as rigatoni just until al dente (typically 10% or so less than package directions) in water that is about as salty as your tears. Transfer the cooked pasta to a large skillet and spoon some of the ragu on top of it. Add some minced parsley and/or basil, some freshly grated cheese, a drizzle of olive oil, and a big splash of the pasta cooking-water. Cook over high heat, tossing constantly, until the sauce is creamy and coast the pasta (add more pasta water as necessary if it looks dry or if the fat breaks out). Serve right away.