Peel the potatoes and slice thinly with a mandoline, or chop into small cube sizes if you prefer a different texture.

Boil potatoes until cooked, about 15 minutes.

Slice onion very thinly.

Combine vinegar, olive oil, garlic, salt, and pepper. Mix thoroughly to make a dressing.

Drain the potatoes and toss with onion in a bowl with the dressing.

Cover with plastic wrap and refrigerate for several hours.

Check seasonings, adding more salt and pepper to taste.

Serve at room temperature.