Vegetable oil (for deep-frying)
1 cup all-purpose flour
1 cup beer
1 teaspoon salt
1 1/2 pounds cod fillets (about 3/4 inch thick), cut crosswise into 2-inch-wide strips
2 pounds russet potatoes, peeled, cut into 1/2-inch wide strips
Malt vinegar or lemon wedges
Pour enough oil into deep-fryer to reach depth of 3 inches. Heat oil to 360 degrees F. Add potatoes to deep-fryer and fry until golden brown and crisp, stirring often, about 8 minutes. Using basket, lift out fries and transfer fries to paper towels. Sprinkle with salt.
Meanwhile, whisk flour, beer and salt in medium bowl until smooth batter forms. Sprinkle fish with salt and pepper. Coat fish in batter. Add fish to deep-fryer and fry until coating is crisp and golden and fish is just opaque in center, about 5 minutes. Transfer fish to paper towels. Sprinkle with salt. Serve fish with fries and vinegar or lemon wedges.