Preheat your oven to 400°F and line a small baking sheet with parchment paper.
Pat the cod fillet dry with a paper towel and season both sides with garlic powder, sea salt, and black pepper.
In a shallow bowl, whisk the egg white until slightly frothy.
Place the almond flour in a separate shallow dish.
Dip the cod fillet into the egg white, then dredge it in the almond flour, pressing gently to ensure the coating sticks to all sides.
Place the coated cod on the prepared baking sheet and bake for 12 to 15 minutes, or until the fish is opaque and flakes easily with a fork.
While the fish bakes, whisk together the olive oil, lemon juice, and Dijon mustard in a small bowl to create the dressing.
Toss the mixed greens with the prepared dressing in a large bowl.
Plate the dressed greens and top with the warm, crispy cod fillet.