Heat a large pot of water to a simmer. Season with the salt and 1 lemon cut in half and squeezed. Add the lobsters and cover with the lid. Cook until the lobsters are bright red, about 7 minutes. Shock the lobster in ice water to stop the cooking.
Add the garlic to the simmering lobster water. Blanch for 2 minutes. Remove from the water and set aside.
Crack and shell the lobster. Cut the lobster into bite-size pieces. Set aside.
Add the mayonnaise, sour cream, Dijon, juice and zest from remaining 1 lemon, 2 tablespoons of the chives, tarragon and black pepper to a small bowl. Smash and chop the blanched garlic and fold it in the mayonnaise mixture. Then add the mayo mixture to the lobster to dress. Mix to combine. Split the rolls and stuff the center with the lobster salad mixture. Brush the sandwiches with the melted butter. Top with the remaining 1 tablespoon chives. Serve!