Finely chop the Scallion (4).
Mince the Fresh Ginger (2 tablespoon).
Pit and chop the Plum (8).
Seed and chop the Chili Pepper (2).
Chop the Lemongrass (2 stalk).
Combine the plums, ginger, lemongrass, chili pepper, scallion, Garlic (2 clove), Soy Sauce (4 tablespoon), Sweet Soy Sauce (4 tablespoon), Honey (4 tablespoon), Rice Vinegar (2 tablespoon), Lemon (4 teaspoon), and Water (1 cup) in a heavy saucepan and bring to a rolling boil over medium heat.
Reduce to medium-low and simmer, uncovered, until plums are very soft, about 5 minutes.
Transfer mixture to a blender to process to a puree, then return to the pan.
Taste for seasoning, adding more soy sauce, honey, or lemon juice as necessary. If too thick, thin with water.
Transfer to a serving bowl and serve warm or room temperature. The sauce will keep, refrigerated, for up to 1 week.