Red kale is prominent among that healthful food category labeled "greens." And while it may seem convenient to group this rich vegetable with other kales, to do so is to ignore its unique color, texture and flavor.
Look for: 12- to 16-inch bundled fronds with stiff central stems. Leaves vary in reddish hue, from bright purple to maroon and mauve with tints of dark green. The varieties have many textures, ranging from dense, crinkly leaves to floppy lobes with round, serrated edges. Most varieties need cooking to bring out their best flavor and palatable texture. Raw, they make terrific garnishes.
A couple of red kale cultivars dominate the market. Red Bor leaves are particularly dense, with a crumpled newspaper appearance. Color varies from prominent bright purple to mottled teal. The flavor is bold and a bit tannic. The color darkens a bit when the leaves are heated, and when sautéing it, add enough oil to the pan to avoid bitter charring. A little dampness on the leaves can prevent burns when it hits the hot pan.
Peacock kale (red and purple varieties) is distinguished by its purple/green variegated, and somewhat flattened, leaves. Its trimmed bulk yields about 20 percent less than Red Bor. The flavor is rich and sweet and holds up well under heat, so you'll often see small sprigs of it in braising mixes. It is also seen with a white variegated leaf.
Some kale leaves in the winter may show dark green or reddish edges, which is a response to cold growing conditions. Although this display is fine, reject bunches that have yellowed or feel wilted. Feel near the twist tie for sliminess or blackened particles, which indicate decay. Avoid bunches that smell of old, wet hay or sulfur.
In season: Year-round, but I find the winter crop has bolder flavor.
To store: Remove the twist tie and dampen the fronds lightly. Enclose them in a plastic bag with the tips of the leaves toward the bottom of the bag and keep for four to five days in the coldest part of the refrigerator.
Basic preparation: Rinse the leaves with cold water and shake dry. Hold the stem at the base and slid the blade of a sharp thin-bladed knife along the stem to cut away the leaves. Repeat on the other side of the stem. Unlike the stems of chard, the stems of most kale varieties are too tough to be edible and are best saved for use in making soup stock or sent to the compost heap. Store leftover leaves in a plastic bag and use them within two days of cutting.