Turn the oven to 350 degrees.Place 1 can of drained tuna, 2 stalks of celery, washed and diced, 1/2 of a small onion, diced, 1 C grated sharp cheddar cheese, 1/4 C mayonnaise in a medium bowl and mix well. Top one half of each hamburger bun( I used 4 ) with 1/4 of the mix. . Place crushed potato chips on each sandwich and top with the remaining bun. Wrap each sandwich in foil and place in the oven for 15 minutes.