Rhubarb by John Spottiswood.

Though a vegetable, rhubarb is treated more like a fruit, and it's typically made into such things as pies, tarts, preserves, and wine. It's very tart, and at its best when combined with berries. Varieties includes cherry rhubarb and the more delicate strawberry rhubarb. Fresh rhubarb shows up in markets in the spring. If you can't find it fresh, frozen rhubarb is a fine substitute. Don't eat rhubarb leaves; they contain high levels of oxalic acid, a toxin.