Preheat the oven to 400˚. Cook the farro as the label directs; set aside. Meanwhile, working with 1 orange at a time, cut off the peel and white pith with a paring knife. Working over a bowl, cut in between the membranes, letting the citrus and juices fall into the bowl.
Lightly coat a 9-by-13-inch baking dish with olive oil. Add the fennel slices, leaving 4 empty spots for the fish fillets. Add the fish curved-side up to the pan; season with salt and pepper and sprinkle with the thyme.
Heat the olive oil and garlic in a small nonstick skillet over medium heat. Cook, stirring, until the garlic sizzles and begins to brown, 2 to 3 minutes. Carefully pour the garlic and oil into the bowl with the citrus and stir well to combine; season with salt and pepper.
Spoon the citrus oil over the fish and fennel. Bake until the fish flakes when poked with a knife at the thickest part, 10 to 14 minutes. Divide the farro among plates and top with the fish, fennel and citrus mixture. Top with fennel fronds.
Farro is packed with protein — it has even more than quinoa! To save time, look for precooked microwavable farro.