Heat the oil in a pan. Sauté the onions and chilli for approx. 1 min. Add the sugar and pour in the water and vinegar. Add the chilli peppers and tomatoes, add salt to taste, bring to the boil. Reduce the heat, cover and simmer for approx. 15 mins. over a low heat until soft. Puree the mixture, leave to cool a little, then chill for approx. 30 mins.
Place the strips of meat on the skewers in a wave pattern. Heat the oil in a frying pan. Fry the kebabs in batches for approx. 4 mins. on each side. Mix the balsamic, rosemary and salt, use to season the kebabs, remove.