If using dry beans, place the beans in a large bowl, cover by 1 inch with water and soak for 8 hours or overnight. Afterward, strain and allow to drain, then rinse with water until the liquid runs clear through a strainer.
Pour the beans into a stockpot with 3 cups of water, cover, turn the heat to high and bring to a boil—watching carefully to make sure that the beans do not boil over. Once boiling, remove the lid and reduce the heat to medium. Use a spoon to skim off any foam that floats to the top. Repeat this step periodically as more foam forms. Cook for 1 hour or until tender.
Strain and rinse once more and allow to cool.
If using canned beans, skip cooking, rinse beans, and begin here. Combine the parsley and garlic in a serving bowl with the salt, pepper, olive oil and vinegar. Toss the beans together with the other ingredients and refrigerate.