1 Preheat oven to 375° F/190° C. Coat a sheet tray with olive oil.
2 Dry the fish fillet using a paper towel. Season them with salt, pepper. Arrange the fillets on the sheet tray and bake for about 25 minutes.
3 Juice the oranges and set juice aside. Remove and discard the peel and pith of the remaining oranges. Using a sharp knife, remove the segments, cut into small pieces, and set aside in a small bowl.
4 Melt half of the butter in a saucepan over medium heat. Add the shallots and cook, stirring, until tender, about 5 minutes. Add the reserved juice and bring to a simmer. Cook until juice has reduced by half, about another 5 minutes.
5 Remove saucepan from heat, and whisk in the remaining butter, a few tablespoons at a time. Stir in reserved orange segments, olives and fresh herbs.
6 Transfer fish to a serving platter or individual dishes, and spoon all of the sauce over the top. Serve immediately.