1 can of canned tuna in its own juice;
1 can of canned beans;
2 large pickles;
1 large fresh cucumber;
1 tablespoon vinegar;
2 tablespoons vegetable oil.
Start with the onion. Cut it in half rings, scald it with boiling water and pour it with vinegar diluted according to the instructions (usually indicated on the package). Set aside, let it marinate. In the meantime, chop the cucumbers, drain the liquid from the beans, take the tuna out of the can and break it into pieces with a fork.
Mix the ingredients together. Take the onions out of the vinegar and add to the salad. Pour the mixture with oil, generously peppered. Be careful with the salt, though: the cucumbers and tuna have already done their part.