Step 1 — Thaw and Steam the Lobster Tails
Thaw the lobster tails completely in the refrigerator overnight. Set a steamer basket over an inch of boiling water in a pot with a tight-fitting lid, add the tails, cover, and steam for 5 to 6 minutes per 5 oz tail, about 1 minute per ounce of tail weight. Transfer the tails to a bowl of ice water for 2 minutes as soon as they're done to stop the cooking.
Doneness guidance: The tails are done when the shells turn bright red and the meat is fully opaque and white throughout. Pull them from the steamer right away. A few extra minutes of carryover heat can toughen the meat.
Step 2 — Remove and Chop the Lobster Meat
Once the tails are cool enough to handle, cut down the length of the underside shell with kitchen scissors. It's thinner than the top shell and cuts easily. Peel back the shell and pull the meat out in one or two pieces. Check for the dark digestive vein along the top of the meat and remove it if present. Cut the meat into ¾-inch chunks. Chunky pieces are the point of a lobster roll, so avoid chopping the meat too finely.
Step 3 — Dress the Lobster
Place the lobster chunks in a chilled bowl. In a separate bowl, whisk together the mayonnaise, lemon juice, lemon zest, and a pinch each of kosher salt and white pepper until smooth. Add the dressing to the lobster and fold gently with a spatula. Vigorous stirring breaks the meat into smaller pieces and turns the filling mushy. Use just enough mayonnaise to bind the lobster without weighing it down. Fold in the chives, then taste and adjust the salt, pepper, or lemon. Keep the mayonnaise light enough that the lobster flavor comes through clearly.
Step 4 — Toast the Buns and Assemble
Spread the softened butter on both flat sides of the split-top buns. Toast them flat-side down in a skillet or griddle over medium heat, pressing gently, for 1 to 2 minutes per side until golden brown. Line each bun with a lettuce leaf if using, then fill with the lobster salad, mounding it slightly above the bun. Serve immediately with lemon wedges and potato chips.