Tip the rice into a bowl. Cover with cold water and whisk for 1-2 mins (you can use a fork) till the water goes cloudy. Drain and rinse the rice under cold water. Tip back into the bowl. Cover with fresh water. Set aside.
Tip the peanuts into a wok or deep frying pan. Toast over a medium heat for 2-3 mins till the peanuts smell nutty and are golden brown. Tip into a tea towel and gently rub to remove as much of the skins as you can. Set aside.
Separate the bok choi leaves. Finely shred the thick stems and keep them separate from the leaves. Shred any large leaves. Trim the roots and top 1cm off the spring onions. Finely slice them. Put the sliced white parts with the bok choi stems and the green parts with the bok choi leaves.
Drain the rice and tip into a small pan. Add 300ml boiling water and a pinch of salt. Cover. Bring to the boil, then turn the heat down and simmer for 8 mins till all the water is absorbed and the rice is tender. Take off the heat. Set aside, lid on, for 5 mins to finish cooking the rice. It will keep warm in the pan for up to 15 mins.
While the rice cooks, tip the chicken into a bowl and add 1 tbsp cornflour. Season with salt and pepper. Toss to coat the chicken in the flour. Warm the wok over a high heat for 1-2 mins. Add 1 tbsp oil and the chicken (shake off any excess cornflour and keep it in the bowl for later). Stir fry for 5-8 mins till golden all over.
Add 1 tsp Szechuan peppercorns and ½-1 tsp chilli flakes (or more if you like, but remember, they're spicy). Add the bok choi stems and the white parts of the spring onions. Stir fry for 2 mins.
Tip in any leftover cornflour. Crumble in the chicken stock cube. Pour in 2 tbsp each rice vinegar and tamari. Add 200ml boiling water. Bubble up, then turn the heat down and simmer for 4-5 mins to cook the chicken through.
Add the peanuts and bok choi leaves to the wok. Toss to mix and wilt the leaves. Divide the rice between 2 warm bowls. Top with the gong bao chicken and garnish with the green spring onion tops to serve.