Serve this dish alongside our Roasted Wild Striped Bass.
With a large knife, cut each fennel bulb lengthwise into four slices. In a large skillet over medium heat, heat butter and oil until sizzling. Lay fennel slices in skillet; cook, turning once, until browned, about 5 minutes per side.
Pour orange juice over fennel; season with salt and pepper. Bring mixture to a boil, then reduce to a simmer. Cook until fennel is tender, about 15 minutes. Add wine, and continue cooking until fennel is very tender and sauce has thickened, about 10 minutes more. Season with salt and pepper, as desired, and serve warm.