It’s easy to find food-grade, GMO-free citric acid online or in bulk-spice stores like SOS Chefs or Kalustyan’s. Kept in an airtight container, the stuff stays fresh just about forever.

Citric acid is a food grade present in some vegetables and ... pans and even cutlery in a container filled with boiling water and three tablespoons of citric acid. Let them soak for about 30 ...