How to Make It
Preheat the oven to 425°. In a large bowl, toss the garlic, chiles, onion, orange, lemon, fennel, 1 tablespoon of the chile powder and the 3 tablespoons of olive oil. Lay the salmon diagonally on a very large rimmed baking sheet. Season the cavity of the salmon with salt and pepper. Stuff the salmon with the tossed aromatics. Tie the salmon with kitchen string at 3-inch intervals. Rub the salmon all over with olive oil, season with salt and pepper and sprinkle with the remaining 1 tablespoon of chile powder. Wrap the head and tail with foil if they touch the side of the oven.
Roast the salmon on the bottom rack of the oven for about 1 hour, until just cooked through and an instant-read thermometer inserted into the thickest part registers 135° to 140°. Remove the salmon from the oven and preheat the broiler. Set the rack 6 inches from the heat source. Broil the salmon for about 3 minutes, until it is richly browned.
With 2 forks, carefully lift off the salmon skin from the top side and reserve. Lift the flesh from the top side of the salmon and transfer to a platter. Lift the skeletal bone from the salmon and discard. Carefully pour off the pan juices into a bowl. Cut the second side of the salmon into sections and transfer to the platter. Discard the aromatics. Serve the salmon with the pan juices, crispy skin and olive oil.