Sautéed Swiss Chard with Golden Raisins and Capers

Trim tough stem ends from Swiss chard. Cut stems crosswise into 1-inch pieces; cut leaves into 2-inch pieces, keeping stems and leaves separate. In nonstick 12-inch skillet, heat oil over medium-high heat. Add onion and cook about 4 minutes or until onion begins to brown. Add chard stems and cook, covered, 5 to 7 minutes or until tender. Stir in raisins. Add leaves to stems in batches, covering skillet after each batch; cook 7 to 10 minutes total or until leaves are tender and wilted, stirring often. Remove from heat; stir in capers.