Marinade:
Cut the chicken into 2 inch cubes, thread 4 to 5 pieces of chicken onto each skewer. Lay them in a wide shallow dish. Mix all the marinade ingredients together, pour over the skewered chicken. Refrigerate and let it marinate for at least 30 minutes.
Sauce:
For the sauce, place the onion, chili, garlic, lemon juice and sugar in a food processor, process until pureed.
Heat the oil in a small saucepan, when the oil is hot, add the puree and cook for about 2-3 minutes, or until the mixture becomes fragrant. Add the remaining ingredients, stirring to combine. Simmer for about 10 minutes or until the sauce is thick and smooth.
While the sauce is simmering, grill the skewered chicken for about 10 minutes, turning as needed.
To serve, arrange skewers on a decorative platter and spoon the peanut sauce over.
Garnish with chopped cilantro and peanuts.