Combine the lemon grass, coriander, turmeric and chilli powder in a glass or ceramic dish. Add the chicken and turn to coat. Cover and place in the fridge for 30 minutes to develop the flavours.
Meanwhile, to make the satay miso sauce, heat the oil in a frying pan over medium heat. Add the onion and cook, stirring, for 10 minutes or until golden. Add the lemon grass and ginger and cook, stirring, for 1 minute or until aromatic. Add the peanuts, coconut milk, miso, palm sugar and soy sauce and bring to the boil. Reduce heat to low and cook, stirring, for 5 minutes or until the sauce thickens slightly.
Preheat a barbecue grill or chargrill pan on high. Thread the chicken pieces evenly onto the skewers. Cook on grill for 2-3 minutes each side or until golden brown and cooked through.
Arrange the cucumber and coriander on serving plates and top with chicken skewers. Serve with satay miso sauce, steamed rice and lime wedges.