Bring a large pot of water to a boil over high heat and season generously with sea salt. Add the orecchiette and cook until al dente. Reserve 1/2 C of the cooking water and drain the pasta.
While the pasta is cooking, remove the ribs from the mustard greens and cut the leaves into thick strips. In a medium or large sauté pan, add the olive oil, garlic, and chili flake. Cook over medium heat until the garlic becomes tender and just starts to show a golden color. Add the mustard greens, a generous pinch of sea salt, and some freshly ground pepper.
With tongs, gently mix and turn the leaves, coating them with olive oil and garlic. Cook until the greens soften, about 5 minutes.
While the greens are cooking, toast the pine nuts in a small, dry skillet over medium heat, shaking the pan frequently, just until they start to turn a golden brown. Immediately transfer them to a plate. Once the greens are done, remove the pan from the heat. Add the lemon juice, lemon zest, and pine nuts. Taste. Season with more sea salt and black pepper if necessary.
Add the pasta to the pan with the mustard greens and toss to combine. Start shaving pecorino romano on the pasta. Add a little pasta water. More cheese. Taste. Keep adding cheese until you get a creamy cheesy coating on the pasta. Season to taste. Finish with a little fresh Italian parsley, a final grating of pecorino romano, and a drizzle of high-quality olive oil.