Step 1 Heat the oil in a 10-inch nonstick skillet over medium-high heat. When hot, add the onions and plums. Cook, covered, stirring occasionally, until the plums disintegrate, about 10 minutes. Add the ketchup, brown sugar, pureed chipotles, salt and reserved pan juices from the roast pork. Stir well. Bring to simmer; cook, uncovered, until hot, about 5 minutes. Taste and adjust seasoning and chipotle puree. (This can be made several days ahead and refrigerated. To serve, gently reheat on the stovetop or in the microwave oven.)