Fry onion in a pan until golden, add garlic for a few mins, add vinegar, and paste for a few mins coating well with the onions, then add the tomatoes and lime juice. Reduce the sauce down by half 10-15 mins depending on quantity of chicken used. Then add the chicken, do not overcook, chicken should be tender, and run through soured cream. The cream will dilute the sauce, check for taste. Serve with Mexican Red rice.