If starting with live 2 lb cooked lobster meat from about 4 whole lobsters, bring a large pot of heavily salted water to a rolling boil. Add 2 lb cooked lobster meat from about 4 whole lobsters and cook for 8–10 minutes until shells are bright red. Transfer to a cutting board, let cool for 10 minutes, then crack and remove all the meat from the claws, knuckles, and tails. Cut into generous 1-inch chunks. If using pre-cooked 2 lb cooked lobster meat from about 4 whole lobsters, simply pat dry and cut into chunks.

In a large mixing bowl, whisk together the ⅓ cup mayonnaise, fresh fresh lemon juice, 1 tbsp fresh lemon juice zest, 1 tsp Dijon mustard (if using), ¼ tsp kosher salt, and freshly ground ¼ tsp black pepper. Fold in the diced celery and 2 tbsp fresh chives finely chopped. Add the 2 lb cooked lobster meat from about 4 whole lobsters chunks and gently toss until everything is evenly coated. Taste and adjust seasoning. Cover and refrigerate for at least 10 minutes to let the flavors meld.

Heat a skillet over medium heat. Spread softened unsalted butter generously on both flat sides of each split-top hot dog bun. Place the buns cut-side down in the skillet and toast for 1–2 minutes per side until golden brown and crisp. Work in batches if needed.

Spoon the chilled 2 lb cooked lobster meat from about 4 whole lobsters mixture generously into each toasted split-top hot dog bun, mounding it high. Dust lightly with 1 pinch paprika for color if desired. Serve immediately with 1 tbsp fresh lemon juice wedges on the side and your choice of kettle chips, coleslaw, or a simple green salad.