Wash the cucumber and eggs thoroughly.
Boil the eggs, let them cool, then peel them.
Slice the cucumber thinly.
Cut the boiled eggs into bite-sized pieces.
Drain the oil from the canned tuna and place it in a bowl.
Put cucumber, eggs, and tuna into a mixing bowl, then add mayonnaise, salt, and pepper.
Mix all ingredients well and plate the salad.