Bring a large pot of salted water to a boil. While you are waiting, cook the pasta sauce.
In a large sauté pan, heat the olive oil over medium heat. Add the onion and garlic and sauté until tender, 3-5 minutes. Add the tomatoes and cook until tender and the juices have been released about 10-12 minutes. Add the asparagus. Cook until tender, about 3-5 minutes. Season with sea salt and black pepper.
Cook the tagliatelle until al dente. Scoop the pasta directly into the sauté pan with the sauce and toss to coat. Toss in a handful of fresh basil and stir to combine. Serve with Parmigiano Reggiano if desired.