Finely grate the zest from the lemon. Juice it. Pour the juice into a large mixing bowl, save the zest for later. Halve the chilli, flick out the seeds and white bits. Dice. Add half the chilli to the bowl with the tamarind paste. Mix.
Stir the chicken into the dressing you’ve just made and set aside for 10 mins to marinate. If you’re using wooden skewers, soak them in cold water for 10 mins so they don’t burn.
Tip the rice into a pan. Pour in 250ml boiling water. Cover. Bring to the boil. Turn the heat down. Simmer for 6 mins till the water is absorbed. Take off the heat. Steam, lid on, for 2-4 mins till the rice is cooked.
Heat the grill to medium. Line your grill pan with foil. Thread the chicken onto the skewers. Grill, turning regularly, for 10 mins till the chicken is cooked through. Baste with the marinade every now and then.
While the chicken cooks, wipe the mushrooms and slice them. Separate the pak choi leaves, slicing any large leaves into strips.
Heat 1 tbsp olive oil in a frying pan. Add the mushrooms and stir fry for 6-7 mins till they’re juicy. Add the pak choi and cook over a high heat for 1-2 mins to wilt. Season.
Fluff the rice and stir in the lemon zest that you saved in step 1. Season with a little salt if you think it needs it.
Serve the skewers with a pile of rice and the stir fried veg. Sprinkle with the remaining diced chilli, if you like a little extra heat.