Fruit Fly Trap
Simple is best.
After trying a large variety of fruit fly traps and bottles, a jar with kombucha (or apple cider vinegar but why would you?) and a drop of soap is the most effective way to prevent and quickly eliminate fruit flies.
But, everything should be pretty. Fill this decorative 8oz mason jar with kombucha and a drop of dish soap, and leave near your brewer. The fruit flies think they are getting a free meal but instead... Replace kombucha mixture every day until fruit flies are under control and then leave out to prevent further issues.