Hollow out top and bottom halves of bread, leaving a 1/2-inch-thick shell. Place bread, cut sides up, on a baking sheet, and broil for 1 1/2 minutes or until toasted.
Place mayonnaise, yogurt, vinegar, and 1/4 teaspoon salt in a medium bowl; stir with a whisk. Add coleslaw, jicama, apple, and jalapeño; toss well to coat.
Place cornmeal and black pepper in a dish. Place milk in a dish. Dip fish in milk. Dredge in cornmeal mixture; shake off excess breading. Sprinkle with remaining 1/4 teaspoon salt.
Heat a skillet over medium-high heat. Add olive oil; swirl to coat. Add fish; cook 3 minutes on each side or until desired degree of doneness. Place 1 fillet in each roll; divide coleslaw among sandwiches.
MyRecipes is working with Let's Move!, the Partnership for a Healthier America, and USDA's MyPlate to give anyone looking for healthier options access to a trove of recipes that will help them create healthy, tasty plates. For more information about creating a healthy plate, visit www.choosemyplate.gov.