Wash the meat, pat dry, and cut them into the thinnest slices possible. Season with salt and pepper, and coat with potato flour.
Cook the rice according to instructions. Drain the pineapple but keep some of the juices for the sauce. Cut the peppers into strips, and the spring onions julienned. Half the chilli, remove the seeds, then finely chop. Peel and grate the ginger.
Prepare the sauce by mixing all sauce ingredients in a bowl.
In a wok or large pan, heat 1 tablespoon of coconut oil, and stir fry all the vegetables (pepper, onion, garlic, chilli, ginger) over high heat for about 3 minutes. Add the drained pineapple and fry together for another 2 minutes, then transfer everything onto a plate.
Add a second spoon of oil to the pan and fry the tenderloin on high heat for about 3 minutes, stirring constantly.
Put the vegetables back into the pan and mix, then add the sauce. Cook over high heat for about 2 minutes until the sauce thickens. Mix occasionally.
Sprinkle with chopped spring onions and serve with rice.