Grilled Cod Tacos with Charred Red Cabbage

Name: Grilled Cod Tacos with Charred Red Cabbage
Ingredients: 1 lb cod filets; 1 small head red cabbage sliced (core kept intact); 1 bunch scallions, root end trimmed; 1 1/2 tablespoons extra virgin olive oil; 1 teaspoon Old Bay seasoning; 1/4 teaspoon garlic salt; 1/4 teaspoon ground black pepper; 8-10 small corn tortillas heated* (or use flour tortillas, if preferred); 2 limes, one sliced in half, the other cut into wedges; 2 avocados, smashed or prepared guacamole; 5 ounces queso fresco cheese, crumbled