Coat the salmon fillets with basil/ginger mixture on both sides and refrigerate for at least 4 hours or overnight.
When ready to cook for serving, combine the soy sauce, orange liqueur, orange rind, and shallot in a bowl; set aside.
Heat olive oil in a skillet over medium-high heat.
Combine the black pepper and sugars in a shallow dish.
Press one side of the salmon fillets into the mixture, then sauté the fillet, sugar-side-down, to caramelize the sugars, for about 2 to 3 minutes.
Then quickly pour the soy mixture into the pan before the sugar burns, stirring to dissolve any caramelized bits floating around the pan.
Turn the fillets over and lower the heat to medium; cover the pan and cook for 5 to 8 minutes longer, until fillets are cooked through (they will be dark pink in the middle).
Remove fillets from skillet and place on serving platter; melt the butter in the pan then add the Marsala, stirring the bottom with a wooden spatula, and simmer for 3 minutes to deglaze the pan, then pour over the fillets.
Decorate with orange slices, serve, and enjoy!
Adapted from a recipe posted to Gail's Recipe Swap by PegW.