Mix all spices together and store in a tight jar. Heat 1 tablespoon vegetable oil in cast iron skillet on medium high heat until very hot, but not quite smoking. Rinse fish fillets and pat dry with paper towel. Rub a little oil on both sides of the fish and sprinkle spice mix on both sides (generously, if you like it hot). Sear the fish in the hot oil for about 1 minute. Flip it and cook the other side. If the fillets are thick, you may need to lower the heat and cover to fully cook the fish. Serve with lemon wedges.