Stir together the mustard and olive oil and season with salt and pepper. Rub this mixture all over the chicken breasts and set aside.
Prepare the wok for smoking by lining it with foil, then add the rice and tea leaves, mixed together. Place a circular rack in the wok and place the wok over a high heat with the lid on. Heat until smoke starts to escape out of it.
Remove the lid and quickly sit the chicken on the rack. Replace the lid and cook for 3 minutes, then reduce the heat to medium and cook for a further 10 minutes. Turn the heat off and let the chicken sit in the wok for a further 5 minutes while you prepare the salsa verde.
Blend all the salsa verde ingredients in a mini food processor or chop them up finely by hand. Tip into a bowl and adjust the seasoning to taste. Serve the chicken warm or at room temperature with the salsa verde on the side and steamed vegetables such as tenderstem broccoli, if liked.