Preheat the oven to 425 degrees.
Pat dry the sliced potatoes as much as you can, place on a large baking sheet, and toss with the avocado oil and seasoning salt. Put the tray in the 425 degree oven for 15 minutes. Stir the fries around and bake another 15 minutes.
While the fries are baking, you can prepare the fish. Sea salt the cod fillets on both sides. Put the potato starch in one bowl, whisk the egg and mustard in a second bowl, and whisk the almond/coconut/rice flours, garlic powder, and Italian seasoning in a third bowl.
Coat one of the cod fillets in the potato starch covering all sides. Dip in the egg/mustard, and then coat with the seasoned almond flour mixture. Place the breaded fillet on a baking sheet, and then continue to bread all the cod fillets. (If you aren't making as many cod fillets, you can just bread the fillets and set them on the same baking sheet as the fries when it is time to bake them).
Once the fries have baked for 30 minutes (15 minutes, stir, 15 minutes), put the breaded cod fillets in the oven and bake both the fish and fries for 15 minutes.
Put the fish right under the broiler for 2 minutes, flip the fish, and broil another 2 minutes. The fries can just hang out in the oven while you broil and crisp up the tops of the fish.
Serve your fish with lemon wedges and homemade tartar sauce (there is a recipe in my new cookbook, Nourished Beginnings), and your fries with your dipping choice such as organic ketchup!