In a bowl combine mango, scallions, fish sauce, gochugaru, ginger, garlic, and cayenne. Stir until ingredients are evenly distributed. Transfer to a resealable bag and close bag. Leave out at room temperature and away from sunlight for 3 days.
After fermentation, transfer mango kimchi to a clean container, cover, and refrigerate until needed.
This recipe is a great side dish or a topping for sandwiches, wraps, or salads.