place shrimp in pot and cover with water. make sure water is about 2 inches above shrimp. Turn heat to med-high and constantly stir the shrimp for 2 minutes. (pls note - the water will never come to a boil)
immediately place shrimp in Ice bath (mixing bowl with ice) to stop the shrimp from cooking.
dice shrimp and put into a small Tupperware container. add diced jalapeno, diced onion, salt, pepper and minced garlic. fully cover mixture with FRESH lime juice (NOT bottled!) cover Tupperware and refrigerate for approx 30 minutes or until shrimp is pink and no longer translucent.
while shrimp is cooking, dice tomato, cucumber, bell pepper, cilantro and pineapple (click here for how to core and cut a pineapple). put in a medium mixing bowl and set aside (or refrigerate if shrimp won't be done for a while!)
cut lime wedges and slice or cube avocado.
drain juice from shrimp mixture and add to the veggie mixture. add the juice of 1 lime (or to taste) to the bowl. Stir and taste. Add salt and pepper to taste.
serve on tostadas, or on romaine lettuce or with tortilla chips! serve with lime wedges and avocado!