Combine all the ingredients in a saucepan and bring to a boil over medium heat. Reduce the heat to medium-low and simmer, uncovered, until the plums are very soft about 5 minutes. Transfer to a blender and puree then return to pan. Taste for seasoning and add additional soy sauce, honey or lemon juice if necessary to taste. The sauce will be sweet, sour and spicy.
Transfer to a bowl and serve warm or at room temperature. It's awesome with ribs or pork.