Directions: Prepare a charcoal or gas grill. The fire should be medium-hot and the grill rack should be about 4 inches from the heat source. Rinse the walleye fillets and pat dry with paper towels. In a small dish whisk together the lemon juice and olive oil. Place several sprigs of rosemary into the cavity of the fillets. Season the fillets with salt and pepper. Grill or broil the walleye about 5 minutes per side, basting several times with the lemon juice and oil. The fish is done when the flesh is white and flaky and an instant read thermometer reads 145 degrees. Discard the rosemary. Plate in either 2 or 4 servings. Drizzle the fillets with the remaining lemon mixture, season with salt and pepper, and garnish with chopped parsley and lemon wedges.
Pat the fish fillets dry with a paper towel and season them on the flesh side with salt and pepper. Sprinkle with fresh tarragon and press it lightly into the flesh to help it stick. Heat a large nonstick skillet over medium flame and melt the butter in the pan, swirling to coat. Place the fillets seasoned side down in the pan, tilting it to make sure the butter surrounds the fillets, and cook for about 3 minutes. Gently flip the fillets (having the skin on helps keep them from breaking up) and cook on the second side until the fish is just cooked through, about 2 minutes. Plate and serve immediately with lemon wedges, if you’re using them.
Set oven for 400 degrees. Cover bottom of baking dish with lemon and onion slices. Sprinkle lightly with salt and pepper. Lay fillets on top. Cover. Bake 20 minutes. Remove cover, combine remaining ingredients, spread over top. Broil 3" below heat until browned.