1Preheat oven to 150°C fan-forced. Season pork. Heat a large frying pan over high heat until hot. Add 1 tablespoon oil and pork, cook for 5 minutes, turning until all sides are browned. Remove to a small greased roasting pan. Combine the stock, hoisin sauce and half the sriracha. Pour over the pork. Cover tightly with baking paper and 3-4 layers foil. Cook, for 2 1/2 hours or until pork is very tender. Stand covered for 20 minutes.
2Meanwhile, heat the frying pan over high heat until hot. Add remaining oil and the mushrooms, sauté 3-5 minutes until light golden. Combine the remaining sriracha with mayonnaise.
3Use two forks to shred the pork, leaving in the stock mixture. Stir in the mushrooms. Cut the cucumber and carrots into matchsticks. Add coriander and toss to combine.
4Spread bun bases with sriracha mayonnaise. Top with salad then a pile of pork and mushroom mixture. Secure the bun top and serve.
Tip: Sriracha is a Thai chilli sauce available from supermarkets and Asian grocery stores.