Fill a medium saucepan with 2 quarts cold water. Add the salt, coriander, peppercorns and lemon wedges, squeezing the juice into the pot first, and bring to a boil. Let boil for 5 minutes. Reduce the heat to a simmer, add the shrimp, and simmer for about 4 minutes, or until just cooked through. Drain the shrimp in a colander, transfer to a bowl, cover and let chill in the refrigerator for at least 1 hour.
When shrimp is chilled, serve with dipping sauce.
Preheat oven to 400 degrees F.
Place tomatillos, onion, garlic, and jalapeno on a half-sheet pan, toss with the oil, and season with salt and pepper. Cook until the mixture is soft, but do not allow it to color, about 15 to 20 minutes. Transfer to a food processor and process until smooth. Add the vinegar, honey, horseradish, and cilantro and pulse just to combine. Season with salt and pepper. Scrape into a bowl, cover, and refrigerate for at least 1 hour before serving.