Remove chicken from pan, cool down. Wash lettuce leaves, thinly slice them. Half the cherry tomatoes or cut bigger tomatoes into smaller bits. In either case remove seeds to be discarded. Chop the chives. Gently mix all together. Make a dressing by mixing the vinegar, olive oil and sugar together. Add dressing over the salad, mix gently. You can make salad without mixing chicken in, serve chicken on top of the salad instead.