Preheat the oven to 275 F (135 C).

In a cast-iron pot, heat the oil and brown the roast on all sides.
Season with salt and pepper, then add the onion and cook until it is golden brown.

In a small bowl, mix all the remaining ingredients and pour the mixture over the roast in the pot.

Bake for 6 hours and turn the roast over halfway through cooking.

Remove the meat from the pot and shred it using two forks on a cutting board.
Return the shredded meat to the sauce and mix well.

Assemble the shredded meat on toasted (or untoasted) buns and serve with coleslaw or your choice of toppings.