Pork Katsu Sandwich

Name: Pork Katsu Sandwich
Ingredients: 12 oz. boneless pork loin, fat trimmed ¼ thick; ⅓ cup shio koji seasoning; 2 tsp. kosher salt; ½ small head of green cabbage, core removed, very thinly sliced (about 3 cups); 2 Meyer lemons or regular lemons; Kosher salt; 2 large eggs, beaten to blend; 3 cups panko (Japanese breadcrumbs); 1 cup all-purpose flour; Vegetable oil (for frying; about 6 cups); Tonkatsu sauce, preferably Bull-Dog, and Dijon mustard (for serving); 8 ½-thick slices milk bread, crusts removed; Shio koji, a fermented seasoning made of rice koji, salt, and water, can be found at Japanese markets, in the Asian foods section of some supermarkets, and online.