Pineapple Citrus Salmon - cooking recipe

Ingredients

1/2 cup pineapple juice
1 lemon, juice and zest of, washed (reserve zest and juice, you'll need 2 Tbs. of zest and 4 Tbs. of juice)
8 (6 ounce) salmon fillets
4 tablespoons brown sugar
2 tablespoons chili powder
2 teaspoons ground cumin
1 teaspoon sea salt
1 teaspoon ground cinnamon
2 tablespoons unsalted butter
1/4 cup flour

Preparation

Combine pineapple juice and 4 Tbs. lemon juice. Add in the salmon filets, cover and leave in the refrigerator for at least 15 minutes, but no longer than 30 minutes.
Preheat oven to 400 degrees. Prepare a baking sheet by lining it with parchment or foil and spray with cooking oil.
Make a rub by combining in a bowl the brown sugar, chili powder, lemon zest, cumin, sea salt, and cinnamon. Reserve a tablespoon of rub.
Remove the filets from the marinade (reserve marinade and add the reserved rub) and rub all sides generously with the brown sugar rub. I usually have just enough rub to do this, but you may find you need more or less rub depending on the size of the filets.
Place the salmon filets on the prepared baking sheet and place in the preheated oven for 15 minutes or until the fish flakes nicely. After removing from oven, allow to sit for 5 minutes.
While the salmon is baking and resting, make the sauce. Melt butter in a saucepan and add flour, sauteeing until all the mixture is well blended. Slowly whisk in the reserved marinade and rub. Allow to simmer gently until thickened. Season with salt and pepper as desired.
Serve with fat rice and steamed or sauteed spinach with the sauce on the side.
I understand that this salmon could be cooked on the grill, but I've never done this!