Pre-heat your oven to 180 degrees Celsius (350 F).
If your pork cheeks have a lot of fat surrounding the meat, trim most of it off because your dish will end up being too greasy.
Put the flour in a bowl and season with salt and pepper. Add your pork cheeks and coat them in the flour.
Heat up a deep oven-proof frying pan or a pot on high heat, add your vegetable oil, get your pork cheeks and shake off any excess flour, then add your place the in the pan. Brown on for 2-3 minutes on both sides until you get a lovely golden colour.
Once the pork cheeks are well coloured, remove from the pan and transfer to a plate. Turn the heat down on the stove to about medium heat, then add your sliced onions. Fry until translucent, then add your garlic and fry for a further minute, being careful not to burn the garlic.
Add your balsamic vinegar and your apple cider. Bring to a boil, then turn down to a simmer. Reduce the cider for about 5 minutes until thick.
Return the pork cheeks back to the pot, then add just enough stock to almost cover the pork cheeks about 3 quarters of the way up. Then, add your thyme, rosemary and bay leaves.
Put in the oven and cook for 2 hours.
Once you have cooked the pork cheeks, remove them from the pot/pan, then transfer to a plate and cover them with foil. Also, now would be a good time to discard the rosemary, thyme and bay leaves.
Put the pan back on the stove (remember it use a tea-towel or mittens to protect your hands) and then continue to simmer the sauce for about 10 minutes until slightly thickened. If you see any fat floating on top, skim it off with a spoon or a ladle.
Once the sauce is done, shred or slice the pork if you want and then serve.