Prepare this Lemon Puree recipe for David Chang's Pan-Fried Soft-Shell Crab dish.
Place sugar and 2 1/8 cups water in a pressure cooker; heat over low heat and cook, stirring, to dissolve sugar. Add lemon zest and flesh to pressure cooker and cover. Bring to 15 PSI (or 2nd ring on most cookers).
Once pressure is reached, set a timer for 35 minutes; reduce heat to maintain pressure. Do not overpressure. Swirl contents periodically to avoid burning. Strain to remove any seeds.
Transfer zest and flesh to the jar of a blender; add 3/4 cup liquid and puree until smooth. Let cool completely before using.