Red mustard greens are pretty much just like green mustard greens, except they have a pretty red tinge to them. Baby mustard greens are fabulous in salads, and the red ones add a lovely hue. When cooked red mustard greens lose their distinctive color as well as the sharp edge of their flavor. As with green mustard greens, you can mellow the flavor by blanching them in salted boiling water for a minute or two, draining, and then using. Or, sauté them without blanching first for a sharper, but still mellowed, flavor. Longer cooking leads to an increasingly mellow flavor.