Step 1

Set wire rack on a sheet pan. Place milk in a shallow dish. Place flour in another shallow dish. Place bread crumbs in third shallow dish. Working one at a time, dip cutlets in milk, then dredge in flour, shaking off excess. Return to milk, then dredge in bread crumbs, pressing to adhere. Place breaded cutlets on a baking sheet.

Step 2

Heat about 1/2 inch oil in a cast-iron skillet to 375°F. Working in batches and adding oil as needed to maintain level, fry cutlets, turning once, until golden brown on both sides, about 3 minutes per side. Transfer to a clean paper-towel-lined baking sheet. Season with salt and pepper when still hot.

Step 3

Spread avocado on bottom bun halves. Top with fried cutlets. Mound half of the cheese on the cutlets.

Step 4

Arrange onion rings on top of cheese. If using chipotles, tear into pieces and arrange on onion rings; alternatively, arrange pickled jalapeños on top of onion rings. Top with papalo and mound the remaining cheese on top. Drizzle with olive oil.

Step 5

Scoop some bread from each of the top buns and discard. Close sandwiches and serve right away.