Whisk all ingredients together in a medium bowl, season with salt and pepper to taste.
Preheat oven to 400 degrees F. Rub each fillet with olive oil, season to taste with salt and pepper, and wrap envelope style in a banana leaf rectangle. Place seam-side down on a sheet pan and roast 8 to 10 minutes. When done, the fish will look a bit undercooked on top but will be firm and opaque. Place the packets seam-side up on a platter and fold back the sides of the banana leaf.
Roasted Vegetable Couscous:
Preheat oven to 400 degrees F. Place the vegetables in a medium baking dish, toss with the olive oil and season with salt and pepper. Roast for 8 to 10 minutes until vegetables are just cooked through. Bring vegetable stock, saffron and 1 teaspoon of salt to a boil in a medium saucepan, let boil for 5 minutes, until saffron blooms and colors the stock. Add the couscous, stir, cover and reduce heat to low. Cook until all liquid is absorbed, 8 to 10 minutes. Place couscous in a large bowl, add the roasted vegetables and parsley and season with salt and pepper to taste. Serve with salmon and ancho chile-ginger sauce. Garnish with diced red pepper and cilantro.