Preheat oven to 175 degrees and place rack in the middle.
Place a large piece of parchment paper on top of a large piece of foil (big enough to completely wrap fish) and transfer to a cookie sheet. Drizzle 1 T of olive oil in the center; sprinkle with salt and pepper. Place fish skin-side down on oiled area. Drizzle with remaining 1 T olive oil, season with salt and pepper, and sprinkle minced garlic over fish.
Start on one side and fold the parchment over fish neatly. Continue folding until fish is tightly enveloped in parchment. Fold foil neatly over parchment to seal paper envelope. Be sure no moisture can escape the packet.
Place in oven and cook until internal temp reaches 135 degrees, approx. 75-90 min, depending on the thickness of the fish.* Insert kitchen thermometer into the thickest part of the fish for an accurate temperature. Rotate pan halfway through cooking time. When done, remove fish from oven and let rest 10 min before opening packet.
If serving warm, carefully transfer to serving platter and serve with your choice of sauce.
If serving chilled, refrigerate and allow to cool completely, approx. 4 hours. Carefully transfer to a serving platter. If making the fish a day ahead, remove from refrigerator 30 min before serving.
* Coho is thinner and will cook faster. Chinook, which is thicker, will take longer.