Shiny and slightly bumpy on the outside, a sweet, juicy yellow-red on the inside. Besides being exceptionally good eating, this is one of the best cooking plums. Use black plums for preserves, compotes, sauces, or tarts. Leave the skins on and your finished product will have a rich, deep purple color. Plan ahead! Our plums arrive firm. They'll soften in 3-5 days at room temperature, or you can speed up the process by storing them in a paper bag. When your plums yield to gentle pressure, they're ready.