Sweat black pineapple, grilled pineapple, shallot, and ginger with butter in saucepan, then add fish sauce, duck stock, pineapple spice mix, citric acid, and charcoal powder.

Continue cooking 5–7 minutes over medium-low heat, taste and adjust as needed, then remove from heat and puree in blender until smooth, pass through chinois, cool, and reserve for service.