Heat the butter and oil in a large skillet (preferably cast iron) for 10-15 minutes over medium heat.
While that is heating, dry the cod with a paper towel. Sprinkle with your salt of choice on all sides. Add cod to the skillet in a single layer and cook for 2-3 minutes. Flip, top with Zesty Orange Ginger sauce, and continue cooking until done (the fish will be opaque and flake easily with a fork; if measuring with a thermometer, pull the fish when it reaches 135º-140º as carryover heat will raise it to 145º). Remove the fillets with a spatula and place on a platter; cover with a paper towel to retain heat.
Let the remaining sauce in the pan simmer until slightly thickened and then spoon on top of the fish before serving. You can also scrape up the fond (the browned, stuck-on bits) from the pan during this time with a wooden spoon and incorporate into the sauce.