How to Make It
Combine the butter, cilantro, ½ teaspoon salt, and ¼ teaspoon pepper in a small bowl.
Prepare the grill. Cut each lobster tail in half, through the center membrane, using a sharp chef’s knife. Grill, meat-side down, until golden brown, 2 to 4 minutes. Flip and top with half the cilantro butter, dividing evenly. Grill, uncovered, until opaque throughout, 5 to 7 minutes more.
Transfer the lobster tails to a bowl and toss with the remaining cilantro butter.