Prepare the shrimp:
Tip:It can be tricky to tell when shell-on shrimp are cooked through, so check them for doneness early on, and don’t rely solely on
the cooking time listed.
In a 6-quart pot, combine 6 cups water and the wine; bring to a boil over high heat. Tie the peppercorns, bay leaves, pepper flakes, and herbs in a piece of cheesecloth to make a bundle. Add the bundle to the pot, adjust the heat to maintain a steady simmer, and simmer for 25 minutes. Add the lemon slices and salt (the broth should be as salty as seawater). Add the shrimp and cook, stirring occasionally, until just opaque throughout, about 3 minutes, depending on the size of the shrimp. To check for doneness, cut through the shell and into the middle of one shrimp with a paring knife. With a skimmer or slotted spoon, transfer the shrimp to a large rimmed baking sheet. Spread them in a single layer and let cool slightly, about 5 minutes. Transfer to the refrigerator and let cool completely, about 1 hour.
Peel the shrimp, leaving the tails intact. Using a paring knife, make a shallow slit down the middle of the back of each shrimp to expose the black vein. Lift out each vein with the tip of the knife and wipe it off with a paper towel.
The sauce may be made up to 2 weeks ahead. The shrimp may be prepared up to 2 days ahead. Store in an airtight container in the coldest part of the refrigerator.