In a shallow container, combine the orange juice, 3 tablespoons olive oil, soy sauce, salt, and pepper. Add the salmon filets, turn to coat with the marinade, then cover the container and marinate in the refrigerator for 4 to 6 hours.
Preheat the oven to 450 F if you want to finish the fish in the oven (continuing on the stovetop is also an option). Heat the remaining tablespoon of oil in a large ovenproof skillet over medium heat. Add the leeks and sauté for about 6 minutes, until slightly softened. Stir in the mushrooms and garlic, season with salt and pepper, and sauté until the mushrooms have released any liquid, and that liquid has evaporated, and the mushrooms have started to brown, 8 to 10 minutes. Turn the mushrooms into a bowl. Carefully wipe out the pan.
In the same skillet, heat the butter over high heat. Remove the fish from the marinade and pat dry with paper towels. Place the salmon skin side down in the pan and cook, without moving the salmon, for about 5 minutes until the bottom is crispy. Transfer the pan to the oven if preheated and roast for another 5 minutes, or until the salmon is done to your liking. Or flip the salmon in the pan and cook for another 3 to 5 minutes.
Serve the warm mushroom leek mixture spooned over the salmon sprinkled with bacon, parsley, and or lemon zest if desired.
Notes
If mushrooms aren’t your family’s thing, you could use chopped broccoli or sliced asparagus instead of the mushrooms. Or sauté the leeks for about 10 minutes, and then add a whole lot (like 3 or 4 cups) of chopped fresh spinach and then sauté the combo for just a minute or two more as the spinach will wilt quickly.
If mushrooms aren’t your family’s thing, you could use chopped broccoli or sliced asparagus instead of the mushrooms. Or sauté the leeks for about 10 minutes, and then add a whole lot (like 3 or 4 cups) of chopped fresh spinach and then sauté the combo for just a minute or two more until the spinach wilts.
If you don’t need to turn on the oven for any other reason, take the option of flipping the fish instead. If you do need the oven on because you are roasting potatoes or whatnot, just finish it by baking or roasting it in the pan. Possibly less perfect in presentation, but a more eco-friendly thing to do if the oven isn’t already in use.