Preheat an indoor or outdoor grill over medium high heat.
Drizzle the cod dish with a touch of olive oil and season it with salt, pepper and red pepper flakes.
Grill the fish on the pre-heated grill for 5-6 minutes on each side until fully cooked. The fish should flake easily and there should be a golden brown crust.
Remove the fish from the grill and squeeze the fresh lime and orange juice over the fish. Adjust salt and pepper as needed.
To assemble, place a few large pieces of the flaked fish into a warmed tortilla, Top with a spoonful of guacamole, a bit of salsa and 2 tablespoons of the curtido. Serve immediately.
For the Curtido
Combine the cabbage, carrot, and onion in a large bowl. Combine the remaining ingredients in a separate bowl and then pour over the cabbage mixture and stir.
Cover and refrigerate for at least 2 hours before serving.
Notes
The curtido needs to be made ahead of time - at least 2 hours. Once you've made it, it can stay in the fridge for up to 3 days.