Stir together the semolina and 1/2 cup warm water in a small bowl until a dough starts to form. Knead the dough on a lightly floured flat surface until it is firm and elastic, adding water as needed, 7 to 8 minutes. Wrap the dough in plastic wrap and let rest for 30 minutes.
Divide the dough into 2 pieces and roll each portion into a long log about 1/2 inch thick. Slice each log into 1/3-inch-long pieces. Using a butter knife, push each piece of dough down and toward yourself, it should curl up slightly. Using your thumb, push the curl in the opposite direction to form a concave shape, and transfer to a rimmed baking sheet lightly sprinkled with semolina flour. Repeat the cutting and shaping process with the remaining pasta dough. Set aside while you cook the lamb.
In a large bowl, mix the ground lamb with the garlic, lemon zest and crushed red pepper; season with 3/4 teaspoon salt and 1/4 teaspoon pepper. Set aside.
Put a large pot of salted water over high heat and begin to bring it to a boil.
Heat the olive oil in a large skillet over medium-high heat. Add the onion and cook, stirring occasionally, until translucent, about 3 minutes. Push the onions to one side of the pan. Add the ground meat mixture; make sure to break the meat up with a wooden spoon and cook until it is nicely browned and no longer pink.
Deglaze with the wine, scraping up any browned bits from the bottom of the pan. Cook, stirring occasionally, until slightly reduced, about 1 minute. Set aside while you cook the pasta.
Cook the pasta in boiling water until al dente, about 2 minutes. Reserve 1/2 cup cooking liquid. Drain the pasta.
Add the cooked pasta, 1/4 cup reserved pasta water and the butter to the lamb mixture, tossing until the butter is fully emulsified and the sauce coats the pasta. Gradually stir in the remaining 1/4 cup of pasta water to the desired consistency. Stir in the peas. Divide the pasta among 4 bowls, top with Mint Pea Pesto, torn mint, cheese and toasted pine nuts.
Mint Pea Pesto:
Add the peas, parsley, mint, garlic, pine nuts, cheese and a generous pinch of salt. Pulse until a chunky paste forms. With the machine running, drizzle in the oil. Continue pulsing until well combined. Season to taste with salt and pepper.