In a large bowl add the sliced cabbage and shredded carrot. In a small bowl combine Greek yogurt, apple cider vinegar, ground cumin, Dijon mustard, and lime juice. Pour the dressing over the cabbage mix and toss to combine. Set aside.
Combine the ingredients for the Blackened seasoning in a small bowl.
Generously season both sides of the mahi-mahi with the blackened seasoning and rub to cover the entire fish. Carefully slice the fish into bite-sized pieces and set aside.
Add the olive oil to a large cast iron or other skillet over medium heat. Once heated, add the seasoned fish and cook until opaque and flaky, approximately 3-4 minutes per side. Remove from heat.
Season the coleslaw with salt and pepper as needed.
Serve fish with the tortillas, coleslaw, sliced radishes and chopped cilantro.