Pound the pork chops with a meat hammer to flatten them to about 1/2" thick.
In a shallow bowl, whisk the milk and egg to combine. Add the panko bread crumbs and flour to two separate shallow bowls (I usually season each with a little salt + pepper). Dredge the pork in flour, then dip in the egg mixture and finally coat with the bread crumbs. You can prepare these ahead of time and refrigerate before cooking.
Heat 1/2" frying oil in a 12" cast iron skillet on high. When the oil is just beginning to smoke, add the breaded pork chops. Cook for about four minutes per side until crispy and done in the center. Transfer to a paper towel lined plate and season with salt + pepper.
Toast the buns. Spray the inside with a little olive oil cooking spray and get them crispy in a hot non-stick skillet.
Spread a small amount of mayonnaise on the buns, then stack the pork, pickles and pickled onions. Serve immediately.