Rinse cranberries under cold water, drain, and set aside. Combine cranberries, brown sugar, apple cider vinegar, red pepper flakes, cinnamon, and ginger in a medium saucepan.

Place the saucepan over medium heat, stirring gently until sugar dissolves. Cook for 5-10 minutes until the sauce bubbles and cranberries pop.

Reduce heat to low and simmer for 10-15 minutes, stirring occasionally until the sauce thickens and cranberries burst.

Remove from heat and let cool slightly at room temperature, then transfer to an airtight container and refrigerate.