Preheat grill to medium-high heat and spray with nonstick spray or wipe down with greased paper towel so it is non-stick.
Prepare cod by patting down to dry, spray with avocado oil (alternatively brush with oil).
In a small bowl, mix together chili powder, cumin, salt, pepper, garlic, and lime juice. Brush onto one side of cod.
Place cod on the greased grill, spice side down. Brush the other side with the remainder of the spice mixture. Cook for 3-4 minutes on each side depending on thickness. Once cod reaches 140F, take off. Let cod cool.
Grill tortillas for about 2 minutes per side or until warmed and have a few grill marks.
In a separate bowl, mix together yogurt, mayo, lime, salt, cumin, paprika, and garlic powder.
Assemble the tacos by laying a tortilla out, add cod, cabbage, avocado, and cilantro. Drizzle sauce on top of tacos. Repeat and enjoy!