Heat a cast iron pan over medium high heat. Add about 1/4" cup vegetable oil to the pan to heat up. Meanwhile, salt and pepper the pork and dip it into the egg and then into the flour to lightly coat. Repeat these steps for the second piece of pork.

Once the pan is hot, carefully lay the pork into the pie and fry on both sides until golden brown and cooked through. Set aside to rest while you prepare the rest of the sandwich.

Lightly salt you sliced yellow onions. Toss to combine and set aside.

Slice your bread in half and lightly toast. Spread a layer of refried beans on one side of the bread. Top with your pork, tomatoes, onions, sliced avocados, and crumbled cheese. Top it all of with a drizzle of sour cream or mexican crema and the top of the bread.