Rosy-red, sweet-tart rhubarb is a harbinger of spring, the first fruit to come into season. Actually, though it's usually treated as a fruit and used mainly in desserts, rhubarb is technically a vegetable. The edible parts are the fleshy, celery-like stalks—in fact, the leaves are poisonous, which is why you'll never see them attached at the market.
When used in desserts, rhubarb needs a good amount of sugar to offset its tartness. The simplest way to cook rhubarb is to simmer it in a little liquid with sugar for a compote or a sauce. Rhubarb releases a lot of liquid as it cooks, so if you plan to use it in a pie or crumble, you need to add a thickener, such as tapioca or cornstarch.
Look for firm, crisp, unblemished stalks with a bright, intense red color. Do note, though, the color, which can range from green streaked with pink to deep red, depending on the variety and the way it was grown, is not an indicator of ripeness or flavor. Fresher stalks will be more intensely flavored. Choose thinner stalks, as larger ones can be overly stringy and tough.
Trim off the ends and any bits of leaves still attached. While the huge ruffled leaves of the rhubarb plant are truly impressive, they're not for eating. They contain oxalic acid, a toxin that should not be ingested in large amounts.
Peel the fibrous exterior only if it's very tough. Cut rhubarb as you would celery, into slices or small dice, depending on the recipe.
Wrap the stalks tightly in plastic and refrigerate them; they should stay crisp for up to five days. You can also freeze sliced or diced rhubarb in plastic bags for up to six months. Frozen rhubarb tends to release more liquid and doesn't hold its shape as well as fresh rhubarb, so use it where texture is not essential, such as in muffins.
When long stalks of rhubarb flood farmers’ markets and produce aisles from April to June, preserve rhubarb by making jam, which requires only a handful of ingredients. The jam can be canned and stored for up to a year.