Add haw flakes (hawthorn candy), pineapple juice, Chinese red vinegar, hibiscus, salted plum, and strawberries. Continue to boil and reduce to thick consistency, about 7 min. Strain.

Boil, stirring occasionally, until haw flakes are completely dissolved, about 6 minutes. Reduce heat to medium; simmer, stirring occasionally, until runny but thick and reduced by one-third, about ...