Fish and Chips with Malt Vinegar Mayonnaise

INGREDIENTS

• 1 cup corn flour or all-purpose flour
• Kosher salt, freshly ground pepper
• 1 cup vegetable oil
• 1 cup chilled club soda
• 2 teaspoons baking powder
• 1/2 teaspoon freshly ground black pepper plus more
• 2 tablespoons malt vinegar, divided
• 1 tablespoon malt vinegar
• Old Bay seasoning, flaky sea salt (such as Maldon), and chopped fresh dill
• Vegetable oil (for frying; about 4 cups)
• Lemon wedges (for serving)
• 2 cups all-purpose flour
• 1 large egg yolk
• 1 teaspoon kosher salt plus more
• French fries (for serving)
• 12 ounces (or more) chilled light lager
• 1 1/2 pounds cod, haddock or pollack, cut into long, 1 1/2"-wide strips
• 1 teaspoon baking soda