In a medium saucepan, boil the shrimp for 1 to 3 minutes, or until cooked. Drain and cool in ice water.
In a medium bowl, mix together the olive oil, lemon juice, vinegar, salt, and pepper. Add the cooked shrimp, bell pepper, snap peas, onion, and parsley, and marinate in the refrigerator for 1 hour or up to overnight.