Preheat oven to 180degC. Heat 1 tablespoon of oil in a large heavy-based oven-proof saucepan, over high heat. Cook the pork for 10 minutes on each side or until browned. Remove and set aside.
Reduce heat to medium. Add the sriracha, vinegar, sugar and water to the saucepan and stir to combine. Bring to the boil. Return the pork, cover with a lid, place in the oven and cook for 1.5hours. Remove from the oven, turn the pork over, cover and return to the oven for another 1.5hours or until tender.
Carefully remove the pork and place on an oven tray. Cover and refrigerate for 2 hours or until completely cool.
Return the saucepan to medium heat and bring the sriracha mixture to the boil. Cook for 8-10 minutes or until thickened. Set aside to cool.
While the sauce is cooling slice the pork into 8 x 1.5cm thick slices. Heat 1tsp of oil in a large non-stick frying pan over high heat. Cook the bacon, turning, for 4-5minutes or until brown and crispy. Set aside and keep warm.
Using paper towel wipe the pan clean. Heat the remaining oil over high heat. Cook the pork slices for 2-3 minutes on each side or until charred and warmed through.
Spread the base of the bun halves with mayonnaise and top with the lettuce, pork, sriracha sauce and bacon. Top with remaining bun halves to serve.