For best results, use a heavy-bottomed skillet, such as cast iron, to achieve the perfect blackening. Ensure the pan is hot before adding the fish. If you prefer a spicier slaw, add a pinch of red pepper flakes or a finely diced jalapeño to the mango mixture. Feel free to substitute other types of fish, such as red snapper or mahi-mahi, for the flounder. The mango slaw can be made ahead of time and stored in the refrigerator for up to 24 hours. Adjust the amount of hot sauce in the lime crema to your personal preference. For a lower-carb option, substitute cauliflower rice for the regular rice.