In a large pot of boiling salted water, cook broccoli rabe for 1 minute, then place into a bowl of ice water. Drain and pat dry.
In a medium skillet over medium heat, heat oil. Add garlic and cook until fragrant, 1 minute. Add broccoli rabe and season with salt, pepper, and a pinch of red pepper flakes. Toss to coat and cook until warmed through, 2 minutes.
Serve with lemon, if desired.
