Rinse the dried hibiscus petals under cool water to remove any dust or impurities.

Bring the water to a boil in a large pot. Add the hibiscus petals, ginger slices, cloves, cinnamon stick, and orange slices, if using. Reduce the heat to low and simmer for 10–15 minutes.

Remove the pot from the heat and stir in the brown sugar until fully dissolved. Let the mixture cool to room temperature so the flavors infuse.

Strain the tea through a fine-mesh strainer or cheesecloth to remove the hibiscus, spices, and ginger.

Transfer the strained tea to a pitcher and refrigerate for at least 2 hours, or until fully chilled. Serve over ice and garnish with an orange slice or a sprig of mint, if desired.