Bring 2quarts of lightly salted water to a boil in a covered pot over high heat. Trim and discard the bottom inch or so of tough stems from the broccoli rabe. Thoroughly rinse the broccoli rabe, then drain it. Add the broccoli rabe to the boiling water, and using tongs, turn it to coat with the boiling water. Cover and cook for about 4 minutes, using the tongs to occasionally turn the broccoli rabe, until it’s cooked to your preference. Drain the broccoli rabe, then transfer it to a large serving platter. Set aside to cool slightly, then cover and refrigerate for about 15 minutes to chill; if you prefer to serve it warm, skip this step.
Sprinkle alittle sea salt and pepper on top, then drizzle the olive oil evenly over the top. Using the tongs, turn the broccoli rabe to coat with the oil. Scatter the garlic and crushed red pepper flakes over the top. Taste for seasonings.
Cut the lemon into wedges. Arrange the wedges around the platter and instruct your guests to squeeze alittle lemon over their broccoli rabe. Refrigerate any leftovers and serve chilled.