Whisk together the vinegar, sesame oil, 1 teaspoon of the sugar and the chilli in a medium bowl. Add the cucumbers and capsicum, tossing to combine. Refrigerate until serving time.
Preheat the griller. Toss the chicken with the ground coriander, pepper and a pinch of salt in a medium bowl; put aside.
Purée the garlic, peanuts, fresh coriander, stock, lime juice and the remaining sugar in a food processor.
Thread the chicken pieces onto 8 skewers. (If using bamboo skewers, soak in water for 30 minutes beforehand, so that they won't burn.) Grill 15 cm from the heat, turning the skewers once, for 5 minutes or until the chicken is cooked through. Serve the satay skewers with the peanut sauce, the cucumber salad and the lemon wedges alongside.