Fish and Corn Cakes with Tartar Sauce

Name: Fish and Corn Cakes with Tartar Sauce
Ingredients: ½ cup mayonnaise; 3 tablespoons finely chopped cornichons or dill pickle; 1 tablespoon whole grain mustard; 2 teaspoons fresh lemon juice; ½ teaspoon sugar; Kosher salt and freshly ground black pepper; 1½ pound skinless firm white fish fillets (such as cod, haddock, or grouper); 2 tablespoons olive oil; 1 large egg; ¼ cup mayonnaise; 1 teaspoon finely grated lemon zest; ½ cup fresh (or frozen, thawed) corn kernels; 2 tablespoons chopped fresh chives; 2 cups panko (Japanese breadcrumbs), divided; ¼ cup (or more) vegetable oil; Lemon wedges (for serving)