1. Combine first 7 ingredients in a medium bowl, stirring well. Add lobster to mayonnaise mixture; toss. Cover and chill 1 hour.
2. Brush butter evenly over cut sides of buns. Heat a large skillet over medium-high heat. Place buns, cut sides down, in pan; cook 2 minutes or until toasted. Line each bun with 1 lettuce leaf; top with 1/3 cup lobster mixture.