Preheat oven to 425°F and line a baking sheet with parchment paper.
Slice the potato into thin wedges, toss with 1 tsp avocado oil, garlic powder, and half the sea salt.
Roast potato wedges for 25 minutes, flipping halfway through until they are tender and golden.
Pat the cod fillets dry with paper towels to ensure the batter adheres properly.
In a medium bowl, whisk together the flour, baking powder, and cold beer until a smooth batter forms.
Heat 2 tsp avocado oil in a large non-stick skillet over medium-high heat.
Dip each cod fillet into the batter to coat fully, then place carefully into the hot skillet.
Sear the fish for 3-4 minutes per side until the crust is beautifully browned and the fish is opaque.
Serve the battered fish alongside the roasted wedges with the remaining salt and pepper.