Wash and clean tomatoes and cucumber. Quarter tomatoes and cut into bite-sized pieces. Quarter the cucumber lengthways and also cut into bite-sized pieces. Cut the spring onions into thin rings with chimneys. Chop the herbs. Dice the feta. Put all the ingredients in a large bowl. Add oil and balsamic vinegar, season with salt and pepper and mix well. The salad should sit in the refrigerator for about an hour.