Bring your water to a boil in a large saucepan. Add the 2 tablespoons salt, and cook the broccolini in batches for 5 minutes, remove with a slotted spoon. Drain.
combine butter, rind, and juice. Stirring with a fork until well blended. return broccolini to pan over medium-high heat; stir in butter mixture, and the remaining 1/2 teaspoon salt and pepper; tossing gently to coat.