Peel and devein the shrimp. Set aside. In bowl combine the lemon juice, ¼ cup of the olive oil, the minced garlic and red pepper flakes. Add the shrimp and stir to coat. Let it sit for 20 minutes. Meanwhile, in a separate bowl combine the pineapple, tomato and onion and parsley. Drizzle on the remaining oil and mix together. Remove the shrimp from the marinade and grill, broil or cook in a cast iron pan until the shrimp are pink. Plate and top with salsa.