Sauce: In a small mixing bowl whisk together pineapple juice, hoisin sauce, honey, soy sauce, vinegar and cornstarch/cornflour. Place to one side and whisk again just before needed.
Pork: Slice tenderloin into thin strips. Pat dry with paper towels then season both sides with a good pinch of salt and pepper. Place to one side.
Cook Cashews: Heat up 1.5 tbsp oil in a large pan or wok over medium heat. Add cashews and fry until deep golden and crunchy, stirring frequently. Careful - they'll go from perfect to burnt very quickly! Remove and leave oil behind.
Cook Pork: Turn heat up to medium high and add in pork slices (you may need to do this in two batches). Cook for around 1-2mins each sides, or until lightly golden and just about cooked through. Remove from pan.
Stir Fry: Add a dash more oil if needed, then add in your peppers and fry for a few mins until they just begin to pick up colour. Add in garlic, ginger and chilli flakes and fry for 1-2mins longer. Turn heat back down to medium, stir in spring onion and pineapple then pour in sauce.
Simmer & Serve: Allow the sauce to simmer for a few mins until it starts to thicken, then stir in the cooked pork and cashews. Serve with rice and enjoy!