Bring a large pot of salted water to a boil. (Use about a Tablespoon of salt.)
While the water is coming to a boil, cut the thick stems off the broccoli rabe just below the first leaf, then cut the broccoli rabe into two-inch long pieces. (You can cook the whole stem, which I think makes a nicer presentation, but it will be easier to eat in smaller bites.)
Put the broccoli rabe into the boiling water for 3 minutes.
After 3 minutes strain in a colander and rinse with very cold water to stop the cooking.
Spin dry in a salad spinner or wring the moisture out of the broccoli rabe using a clean dish towel. Or if you do this part early in the day, you can lay the stems out on a clean, dry dish towel.
Heat a large sauté pan on medium heat, then add the olive oil.
Once the olive oil is shimmering, add the garlic and the pepper flakes. Sauté until the garlic is fragrant, but not browned.
Add the Broccoli Rabe and the salt and toss to coat the rapini with the oil. Cook for 10 minutes until tender but not mushy, stirring occasionally. (Sometimes I find I need to add a bit more oil.)
Remove from heat, add salt to taste, and more red pepper flakes if you desire, and serve.