4 (4 ounce) skinless mahi-mahi fillets 1 teaspoon chili powder ½ teaspoon ground pepper 1 tablespoon extra-virgin olive oil ½ teaspoon salt, divided 1 avocado ⅓ cup plain whole-milk Greek yogurt ⅓ cup water 2 tablespoons lime juice 6 (6 inch) corn tortillas, warmed ½ cup jicama matchsticks 1 red Fresno chile or jalapeño pepper, seeded and sliced ½ cup loosely packed fresh cilantro leaves
Sprinkle fish evenly with chili powder and pepper. Heat oil in a large nonstick or cast-iron skillet over medium-high heat. Add the fish; cook until golden brown and cooked through, about 3 minutes per side.
Transfer to a paper-towel-lined plate; sprinkle evenly with 1/4 teaspoon salt. Set aside.
Place avocado, yogurt, water, lime juice and the remaining 1/4 teaspoon salt in a blender; process until well combined and smooth, about 30 seconds.
Use a fork to flake the fish into large pieces.
Top tortillas with the fish, jicama, the avocado sauce, sliced chile (or jalapeño) and cilantro. Serve immediately.