This is a super-simple but delicious snack that my grandmother (Tita) would give me either by itself or along with a heaping plate of arroz con habichuelas (rice with beans).
Peel and slice cucumber into 1/4-inch slices/rounds. (Tita used to cut the seeded centers out of the cucumber slices for me. This is not necessary, but I think it's better. You can also buy a seedless cucumber.).