This is a really cool thing to do. Make a tuna salad, dig out the middle of cucumber slices, and put the tuna in. It is a really easy way to make your food look fancy, without a whole bunch of work. :)
For the cucumber, cut the cucumbers into 1 inch slices. Use a 1/4 tsp. to scoop out the middle. Leave some at the bottom or your tuna will fall out.
Scoop the tuna into the cucumbers, place a leaf of dill on top, place on a fancy dish, and viola! A fancy looking snack fit for a queen! :)