Bring a pot of water to a boil.
In a large skillet heat garlic, tomato, and pepper flakes in oil. Add shrimp and sauté till pink. Add salt and pepper.
Cook pasta for 3 minutes. Before draining, ladle 1/2 cup cooking water into skillet.
Drain pasta, adding to skillet with lemon juice, zest and parsley. Salt and pepper to taste.