Turn heat to medium-high. Add the Broccolini to the pan; cook until bright green and some of stems and tips are lightly charred, turning occasionally, about 5 minutes. Add the garlic, salt, and black pepper; cook until the garlic is fragrant, about 30 seconds. Carefully add 2 tablespoons water. Cook, covered, until Broccolini is crisp-tender, 1 to 2 minutes.