Cut chicken breasts into 2 inch long strips. Lightly pound out with a meat mallet to flatten the strips to a inch thick.
For the marinade, combine the ground coriander, ground cumin, chopped garlic, grated ginger, fish sauce, curry powder, turmeric powder, coconut milk and brown sugar to form the marinade. Marinade the chicken overnight or at least 6 hours. Thread the chicken on presoaked skewers and grill on barbeque over fairly high heat. Turn them regularly and brush them liberally with the remaining marinade. Cooking should take between 5 and 10 minutes depending on the heat of the barbecue.
For the peanut sauce, in a saucepan, heat the oil on medium/low heat and fry the onions and garlic for 2 minutes. Add the curry paste and cook for another minute. Add the peanuts, peanut butter, coconut milk, curry paste, fish sauce and stir until smooth. Take off the heat and add the lime juice to taste.
For the cucumber sauce, combine the sugar, vinegar, cucumber, shallot, chili, and refrigerate overnight.