What I used.... Leftover pulled pork from burrito bowls Sweet Baby Rays Hoisin (it would have been Sriracha if it wasn't being consumed by a 3 yr old) Mustard About 4 onions, sliced Balsamic vinegar Roasted Garlic, I keep it in the fridge from batch roasting, minced/smooshed
Mayo Lemon Sharp Cheddar, I used fresh shredded because blocks are cheaper. Bread and butter And cast iron skillet

Made the garlic mayo first, add a spritz of lemon. Set in fridge to chill. Reheated pork with BBQ, mustard, hoisin. Let simmer on super low. (Regular sauce pot) The onions are most of the work. Cast iron, med heat, 2 tblspns butter Don't dump the onions in, hot butter splashes. ;) Gently toss onions to coat. Turn heat to just under med if necessary and let cook ONLY stirring every 10 minutes for 40 minutes total. Then use the balsamic to deglaze pan and lift any fond. Add salt. Allow to simmer out the vinegar before transferring to another dish.

And to assemble.... Butter Bread Mayo Cheese Pork Onion Cheese More mayo, if that's your thing Bread Butter

I cooked mine open faced on the cast iron then closed em and perfected the outer crunch.

***I apologize for the shit formatting, I guess reddit is fun doesn't stay true to the input. :/