This is a ceviche-style dish that calls for letting the fish stay in the marinade before serving. One of my favorite things to do is to suck out the heads of the shrimp. In Italy this is a major compliment to the chef. It's also very flavorful.
Shell and clean your shrimp, leaving the heads on. Lay the shrimp out on a plate and squeeze the lemon juice on top, followed by some salt, black pepper, chili flakes, if using, and a good splash of olive oil (this will partially cook the shrimp). Let the shrimp marinate 10 minutes, if desired, or serve immediately. Garnish with fresh parsley.
Consumption of raw or undercooked eggs, shellfish and meat may increase the risk of foodborne illness.