Fish and Chips with Malt Vinegar Mayonnaise

Name: Fish and Chips with Malt Vinegar Mayonnaise
Ingredients: 1 large egg yolk; 2 tablespoons malt vinegar, divided; 1 cup vegetable oil; Kosher salt, freshly ground pepper; Vegetable oil (for frying; about 4 cups); 2 cups all-purpose flour; 2 teaspoons baking powder; 1 teaspoon baking soda; 1 teaspoon kosher salt plus more; 1/2 teaspoon freshly ground black pepper plus more; 12 ounces (or more) chilled light lager; 1 cup chilled club soda; 1 tablespoon malt vinegar; 1 cup corn flour or all-purpose flour; 1 1/2 pounds cod, haddock or pollack, cut into long, 1 1/2-wide strips; French fries (for serving); Old Bay seasoning, flaky sea salt (such as Maldon), and chopped fresh dill; Lemon wedges (for serving); Ingredient info: Corn flour, which is more finely ground than cornmeal, is available at Latin markets, natural foods stores, and bobsredmill.com.; A deep-fry thermometer