Prepare an ice bath in a large bowl and set it aside. This will be used to stop the cooking process of the shrimp and calamari immediately after poaching, ensuring they remain tender.

In a large pot, bring the white wine to a simmer over medium heat. Add the cleaned mussels, cover tightly, and steam for 3-5 minutes until the shells open. Shake the pot occasionally. Remove from heat, discard any mussels that did not open, and let cool slightly. Remove most of the mussels from their shells, leaving a few in the shell for presentation if desired. Set aside.

In the same large pot (rinsed out), combine the water, lemon chunks, bay leaf, whole peppercorns, and 1 tablespoon of kosher salt. Bring to a rolling boil over high heat.

Reduce the heat to medium so the water is at a gentle simmer. Add the calamari rings and tentacles. Poach just until opaque and firm, about 1 to 2 minutes. Do not overcook or they will become rubbery. Use a slotted spoon to transfer the calamari immediately to the ice bath. Let cool completely, then drain well.

Return the poaching liquid to a gentle simmer. Add the shrimp and cook until pink and opaque throughout, about 2 to 3 minutes. Transfer immediately to the ice bath. Let cool completely, then drain well along with the calamari. Pat all seafood thoroughly dry with paper towels.

In a large mixing bowl, whisk together the extra virgin olive oil, fresh lemon juice, minced garlic, chopped parsley, sliced celery, red pepper flakes, salt, and black pepper.

Add the drained, dried calamari, shrimp, and shelled mussels to the bowl with the dressing. Toss gently but thoroughly to ensure all the seafood is evenly coated.

Cover the bowl tightly with plastic wrap and refrigerate for at least 2 hours, or up to overnight. This resting time is crucial as it allows the seafood to absorb the flavors of the lemon, garlic, and herbs.

Before serving, taste and adjust seasoning with additional salt, pepper, or a squeeze of lemon juice if needed. Serve chilled or slightly cooler than room temperature.