In a medium pot, bring 4 cups of water to boil, turn off the heat, drop in the shrimp and cover. Leave the shrimp in the hot water for 1 minute. Drain off the water and place the shrimp in a plastic bowl.
Add the ketchup, lime juice, onion, cilantro, parsley, Tabasco sauce, olive oil, garlic, salt and pepper to taste. Stir to combine all ingredients. Refrigerate and serve cold over lettuce leaves with saltine crackers.