Mince the garlic, finely chop the red chili pepper and chop the parsley. Mix with lemon juice, olive oil, salt, and pepper. Set aside some of the garlic for the sauce and mix the rest with the gray shrimp. Let marinate for 10–15 minutes.

Bring a pot of water to a boil, add salt, and cook the tagliatelle until al dente. Reserve some pasta water and drain the pasta.

Heat olive oil in a pan over medium heat and briefly fry the marinated gray shrimp until they turn pink. Remove them from the pan and set aside.

Add the reserved garlic to the same pan and fry very briefly until fragrant, then add a splash of the reserved pasta water and reduce the heat to low to form a smooth sauce.

Return the tagliatelle and the gray shrimp to the pan with the sauce, add Parmesan, and toss until glossy. Add more pasta water if the sauce is too thick.

Season with pepper, salt, and extra lemon juice to taste, sprinkle with parsley, and serve immediately.