Broccoli rabe isn't actually related to broccoli. Instead, it's closely related to the turnip. And the best way to approach it is just as you would with bitter leafy greens, like mustard greens or turnip greens.
How to Select
Broccoli rabe is most plentiful between late fall and early spring. This long, slender vegetable, which may also be referred to as broccoli raab and is similar to rapini, has thin stalks with deep-green leaves and small buds that resemble broccoli florets. Broccoli rabe is sold fresh in grocery stores and farmers markets, and is at its peak in the cold months of winter. At the market you'll usually find broccoli rabe displayed in a refrigerator case sprinkled with ice because it wilts very easily. Choose firm, green, small stems with compact heads. Like broccoli, the flower buds that make up the florets should be tightly closed and dark green, not open or yellow
How to Store
Store broccoli rabe in your refrigerator crisper unwashed, either wrapped in a wet towel or in a plastic bag. It will keep two or three days. For longer storage, blanch and freeze.
How to Prepare
Although the flavor mellows somewhat as it cooks, broccoli rabe has a bitter taste that's also a bit earthy and nutty. It's particularly popular in Italian cuisine, and best when sautéed or blanched to soften the stalks and leaves. To prepare, rinse thoroughly in cold water, shake off, and cut off the bottoms of the stalks (they're too tough to eat). Broccoli rabe is much better cooked than raw. Raw, it's very bitter but has no flavor. Even a light steaming brings out its distinctive taste. As a side vegetable, broccoli rabe yields only about one serving per pound because it cooks way down.