1. Partially thaw out shrimp block under running water. Break into large portions.
  2. Retrieve a 3 lb. portion then freeze or set aside rest to use for another recipe. Or thaw and peel whole box, and refrigerate remainder for other use in a day or meal ahead. Thaw out recipe portion in unchlorinated water bath.
  3. Rinse, and peel shrimps, rinse once more, and set aside. Any black veins too prominent, remove as needed. Freeze shrimp skins for future use in preparing a seafood bouillon, bisque, or sauce flavoring then discard.
  4. To prepare cocktail sauce place chili sauce, lemon peels, lemon juice, horseradish, black pepper, and optional hot sauce in a small glass bowl. Whisk until well combined. Cover and chill until ready to serve. Whisk quickly before serving. Taste and adjust to need. Sauce can be made up to 1 day ahead. Keep chilled.
  5. Place 6 cups water in a large stainless steel saucepan. Turn burner up to medium high. Whisk in salt and sugar. Stir for ½ minute. Prepare each peeled garlic clove by slicing multiple times ½ through (leave clove whole). Stir in garlic, onion, white and black peppercorns and optional tarragon. Break in half and add bay leaves. Cut lemons in half, squeeze juice into pot, then toss in squeezed lemon halves. Cover, turn on to high, and bring liquid to a boil. Periodically uncover, stir to completely dissolve salt and sugar, and re-cover. Let soft boil 15 minutes. Give quick stir every 5 minutes.
  6. Scoop 8 cups ice cubes into a large bowl, and set aside.
  7. Remove pot from heat. Add shrimps and poach, uncovered, 4 minutes. Other Shrimp poaching guidelines: For U26–30 ct, poach 1½ minutes. For U21–25, poach 3 minutes. Cook until bright pink. Turn off heat and immediately add ice cubes to pot. Ice rapidly chills the liquid and stops the cooking process.
  8. Let shrimp sit in ice bath 10 minutes. Drain and pat dry. Cover and chill until ready to serve. Do Ahead: Shrimp can be peeled and poached 1 day before. Keep chilled.
  9. Serve shrimp plated with cocktail sauce on the side or on cracked ice, with lemon wedges and cocktail sauce. Fancy-serve portion: hung from side of margarita glass filled with ice with centered cocktail sauce filled small s/s cup for dipping. Offer additional condiment(s), * Garlic Butter, or ** Salsa Brizano, as desired Serve with wine of choice… traditional favorites are a good Riesling, Prosecco, or Sauvignon Blanc.