Pork Tonkatsu

Name: Pork Tonkatsu
Ingredients: 1/4 cup ketchup; 1/4 cup apple butter or applesauce; 1 tablespoon Worcestershire sauce; 1 tablespoon low-sodium soy sauce; 1 teaspoon Dijon mustard; 1 teaspoon unseasoned rice vinegar; 1/4 cup all-purpose flour; 2 egg whites, beaten; 1 cup panko (Japanese bread crumbs); Two 8-ounce pork tenderloins, cut into 2-inch pieces and pounded 1/2 inch thick; Salt; 1/4 cup canola oil; Steamed rice and steamed spinach, for serving