Step 1 Fill large pot with enough water to completely cover lobsters. Add vinegar and bring to boil. Remove from heat and submerge lobsters.
Step 2 Steep lobsters 2 to 3 minutes. Remove lobsters from water, twist to remove knuckles and claws and return these to hot water.
Step 3Separate tails from body of lobster (reserve body for stock or discard). Cut through cartilage on underside of lobster, pull apart and pull out tail meat in 1 piece. Cut tail in half lengthwise, remove vein and trim any loose strands. Remove claw meat intact by wiggling off small lower claw, to which a piece of cartilage is attached (be sure to remove this cartilage if it separates) and by cracking fat claw near its base to open and remove meat without damaging it. Remove knuckle meat and reserve for another use (it's great sauteed quickly in butter for a snack). Place all meat on paper-towel-lined plate, cover with plastic wrap and refrigerate until ready to use. (Allow lobster meat to sit at room temperature 1 hour before cooking if chilled.)
Step 4To make beurre monte, bring 2 tablespoons water to simmer in large saucepan. Whisk in butter, 1 piece at a time, reducing heat to low and being careful not to boil butter. Submerge lobster tail in butter and poach over low heat until heated through, 5 to 6 minutes. (Optimum temperature of beurre monte is between 180 and 190 degrees.)
Step 5While lobster poaches, saute shallot in 1 teaspoon beurre monte over medium heat, 2 to 3 minutes.
Step 6When lobster is cooked, remove to warm plate, add 1 cup beurre monte to shallots, then add herbs. Heat over medium heat until beurre monte is hot but not boiling.
Step 7To serve, place 1 claw on top each half lobster tail and serve with sauce in warm dish. (You'll use about 1 cup. Leftover lobster-infused butter can be refrigerated, clarified or not, and reused for sauteing.)