Fish and Chips with Malt Vinegar Mayonnaise

Name: Fish and Chips with Malt Vinegar Mayonnaise
Ingredients: 1 large egg yolk*; 2 Tbsp. malt vinegar, divided; 1 cup vegetable oil; Kosher salt and freshly ground black pepper; Vegetable oil (for frying; about 4 cups); 2 cups all-purpose flour; 2 tsp. baking powder; 1 tsp. baking soda; 1 tsp. kosher salt plus more; ½ tsp. freshly ground black pepper plus more; 12 oz. (or more) chilled light lager; 1 cup chilled club soda; 1 Tbsp. malt vinegar; 1 cup corn flour or all-purpose flour; 1½ lb. cod, haddock or pollack, cut into long, 1½”-wide strips; French fries (for serving; click for recipe); Old Bay seasoning, flaky sea salt (such as Maldon), and chopped fresh dill; Lemon wedges (for serving)