1. In a large saucepan, add potatoes, cover with water 1 inch above tops, and bring to a boil over high heat. Add 1 tsp. salt, adjust heat to medium-low, cover pot, and simmer for 15 minutes. Remove from heat and leave potatoes in water until they're tender (when you can pierce them with a paring knife with little resistance), about 15 minutes longer. Reserve 1/4 cup of the cooking water and set aside, then drain potatoes. While potatoes are still hot, peel them by spearing them with a fork while you slip off the loose skin with a paring knife. Cut potatoes into 1-inch chunks, return them to the pot, sprinkle with 2 tsp. vinegar, and mix.
2. Whisk mayonnaise, garlic, remaining 1 1/2 tsp. vinegar, and pepper in a large bowl. Add 2 Tbsp. reserved potato cooking water and whisk to loosen mayonnaise (texture should be similar to applesauce); if mayonnaise is still too stiff, add additional potato water 1 Tbsp. at a time. Add potato chunks and gently fold into mayonnaise to blend. Add parsley, adjust seasoning with extra salt and pepper if desired, stir to combine, and serve warm or at room temperature.
Source: Hannaford fresh Magazine, May - June 2008