Tip the rice into a large bowl. Cover with cold water and whisk for 1-2 mins till the water is cloudy. Drain, rinse and tip into a small pan. Add 300ml boiling water and a pinch of salt. Cover and bring to the boil.
Turn the heat down to low. Very gently simmer the rice for 8 mins till all the water is absorbed and the rice is tender. Tip into a sieve and rinse under cold water to cool it. Leave in the sieve to drain and cool while you prepare the rest of the dish.
While the rice is cooking, toast the cashews in a dry wok or deep frying pan for 3-4 mins, shaking the pan, till they’re browned all over. Tip into a bowl and set aside for later.
Prepare the veg: trim the very ends off the leek, rinse out the grit and finely slice it. Halve the pepper. Scoop out the seeds and white bits, then roughly chop. Shred the sprout top, discarding any thick stem. Peel and grate the garlic and ginger. Finely chop the chilli, flicking out the seeds and white bits.
Whisk the eggs together. Add 1 tbsp each of the brown rice vinegar and tamari. Whisk again and set aside. Heat the wok or frying pan for 1 min. Add 1 tbsp oil. Pour in the beaten eggs. Swirl to coat the base of the pan. Fry for 2-3 mins till set.
Use a spatula to lift the edge of the omelette and roll it up. Slide out of the pan and set aside. Add ½ tbsp oil to the pan with the leek and pepper. Stir fry for 5 mins till the veg are softened. Add the rice and sliced sprout tops. Stir fry for 3-4 mins till the sprout tops are wilted.
Add the garlic, ginger and chilli to the pan with 1 tbsp of the remaining rice wine vinegar and the rest of the tamari. Stir fry for 1 min. Slice the rolled omelette and add to the pan. Stir to mix everything together. Taste and add the remaining tamari if it needs it.
Spoon the rice into warm serving bowls. Roughly chop the toasted cashews and scatter over the special fried rice. Drizzle with Thai sweet chilli sauce and serve.