Classic British Fish and Chips

Name: Classic British Fish and Chips
Ingredients: 1 quart cold tap water; 2 tablespoons , plus 1 teaspoon kosher salt , divided; 4 (5 1/2-ounce) skinless cod fillets; 1 teaspoon ground white pepper; 1 1/4 cups (about 5 3/8 ounces) all-purpose flour , divided; 2/3 cup sparkling water; 1/2 cup brown ale (such as Newcastle Brown Ale); Maldon sea salt , to taste; 2 medium lemons , cut into wedges; 2 large pasteurized egg yolks; 2 tablespoons Dijon mustard; 2 teaspoons white wine vinegar; 2 cups vegetable oil; Tap water , as needed; 1 1/2 teaspoons fresh lemon juice (from 1 medium lemon); 1/2 teaspoon kosher salt; 1/4 teaspoon cayenne pepper; 1 tablespoon chopped gherkins (from 3 small gherkins); 1 tablespoon finely chopped capers; 1 tablespoon finely chopped shallot (from 1 small shallot); 1/2 teaspoon finely chopped fresh tarragon; 1 teaspoon finely chopped fresh flat-leaf parsley; 1 teaspoon finely chopped fresh chervil; 4 large (14-ounce) russet potatoes; 1/4 cup kosher salt , plus more to taste; Canola oil; Mushy peas