Place the Mahi Mahi in a shallow glass bowl. Whisk together the next six ingredients and pour over the fish. Let marinate at room temperature for 15 to 30 minutes.
Meanwhile, toss the kale, cabbage, and carrot in a bowl. In a small bowl, whisk together the orange juice and olive oil. Add the vinaigrette to the slaw and toss until evenly coated. Season with salt and pepper to taste.
Heat a grill pan over high heat. Season both sides of the fish with salt and pepper and grill for about 4 minutes per side, or until white and flaky. Remove to a platter, drizzle with a bit of olive oil, and serve with lime wedges.
To serve: Create a taco buffet, either on your table on the counter, with a stack of warm corn tortillas (keep covered with a damp cloth so they don’t dry out), a platter of grilled fish, and bowls of sliced avocados, black bean spread, marinated onions, and kale slaw.