Hands-down, the best place to eat in Union and possibly all of Monroe County. (And I have tried all three eateries in Union, though not the few others there are in the county.) Serving burgers, chicken tenders, Philly sandwiches, chef and taco salads, and the like, plus basic, traditional breakfasts.
Most of the food is processed in part or whole, and condiments and dressings come in plastic single-serve containers. But salads and fixin's are fresh, and quality is consistently good. Your cheeseburger will be a processed patty with processed American cheese on a processed bun; but will be made as well as such ingredients can be, and the lettuce, tomato, onions, and pickle will be crisp and fresh. I've also enjoyed the daily specials I've tried - and the daily dessert pies. Which may be made a little more from scratch. I recommend the specials over the regular menu.
The decor is also the best in town, casual country style, with wood tables, tin ceiling, big old-time display windows, and country tchotchkes.
Prices are super cheap, ranging from $4 to $7 for lunch/dinner entrees.
Reviewers elsewhere have called the service unfriendly. But it's fine. Just a little workaday, reserved with strangers, and lacking more practiced artifices of hospitality.
Korner Kafe is closed evenings after six or seven and Sundays. Don't confuse it with the lesser Kalico Kitchen down the street.
Food 4 + ambiance 6 + value 9 + service 5 = overall 5.4 /10 (decent/forgettable)