How to Make It
Season the fish with salt and pepper. Arrange 1 slice of prosciutto and 1 sage leaf on the flesh side of each fillet; secure with toothpicks.
In a medium bowl, stir the flour with 1/4 teaspoon each of salt and pepper.
In a large nonstick skillet, heat the olive oil. Dredge the fish in the flour mixture, shaking off the excess. Add the fish to the skillet, prosciutto side down, and cook over moderate heat until golden, about 3 minutes. Flip the fish and cook until golden and just opaque throughout, 3 to 4 minutes longer. Transfer the fish to plates and remove the toothpicks.
Add the wine to the skillet and cook until reduced by half, 1 to 2 minutes. Whisk in the butter and season with salt and pepper. Spoon the sauce over the fish and serve warm.