Step 1

Preheat oven to 325 degrees F (165 degrees C).

Step 2

Drizzle 1 tablespoon olive oil into a large baking pan; add onion and season with salt and pepper.

Step 3

Place the 2 cleaned fish into the baking pan and stuff each cavity with 1 lemon wedge, 1 rosemary sprig, and some of the red onion. Pour white wine and lemon juice over each fish and sprinkle with oregano. Drizzle the remaining 1 tablespoon olive oil over the 2 fish.

Step 4

Bake in the preheated oven until fish is opaque and flakes easily with a fork, about 25 minutes. Gently slide a spatula between the bones to separate fish; remove all the bones. Serve fish on a platter and garnish with parsley and lemon wedges.