1. Fill a five-quart pot with water and bring to a boil over medium-high heat. Add broccolini and cook for three minutes. Drain and rinse under cold water.
2. Heat oil in a large cast-iron skillet over medium-high heat. When oil is hot, add broccolini and cook undisturbed for two to three minutes. Flip broccolini and cook on the other side for approximately two minutes. Add garlic, lemon zest and juice, crushed red pepper, salt, and pepper and cook for two more minutes, until broccolini is soft and lightly browned but still holds its shape.
3. Serve warm.