In a fine mesh strainer or colander, drain and rinse the beans with cold water. Add the beans to a medium bowl.
Rinse some fresh parsley and snip the leaves off the stems until you can measure out ¼ cup of loosely packed parsley. Add the parsley to the bowl of beans.
In a liquid measuring cup, add the vinegar, olive oil and seasonings. Whisk them to blend, then pour the dressing over the beans. Toss the bean salad with two spoons to mix it.
Serve the bean salad at room temperature or slightly chilled. Store leftovers in the refrigerator for up to five days. Stir the bean salad again before serving it.
Notes
Rinsing and draining the canned beans gets rid of unwanted chemicals and sodium.
This is a cold bean salad, but it's best to take it out of the refrigerator for 20-30 minutes before serving until it's nearly room temperature. The olive oil in the dressing will solidify a bit in the fridge, so it needs a chance to thin out.
Variations
For Italian white bean salad, skip the black beans and use just cannellini or a combination of cannellini and ceci (chickpeas). Feel free to add some chopped tomatoes or even a little red onion.
For 5-bean salad, you'll need to add two more kinds of beans. Try pinto and cooked green beans. You might as well double the dressing, since you'll have nearly double the amount of beans.
For 7-bean salad, you'd add another two types of beans. Consider options like butter beans and wax beans. Start with doubling the dressing and then see if you need to splash on a little more vinegar and add more seasonings.