Place shrimp in bowl with cold water for 5 to 10 minutes or until defrosted. Place all poaching ingredients (water, lemon, lemongrass stalks, garlic, ginger, kosher salt) into a stockpot over high heat, bring to a boil, and let cook for 10 minutes. While poaching liquid is cooking, begin to prepare your cocktail sauce. In a medium size bowl, place chili sauce, pineapple concentrate, and wasabi, mix well, pour into serving container, set aside in the refrigerator. (If you would like more of a wasabi punch in your cocktail sauce, add more to desired level).
Once the poaching liquid has cooked for 10 minutes, turn to low heat, add defrosted shrimp, and cook for 3 to 4 minutes or until done. Meanwhile, get a medium size bowl and fill half with water and ice. Once shrimp is finished, pour out poaching liquid in a colander and discard. Place the shrimp in the ice bath for 5 minutes or until chilled – this will stop the cooking process. Take the shrimp out of the ice, dry them off and serve with the cocktail sauce