Source: Martha Stewart Living magazine, April 2010
2 lbs. red potatoes, scrubbed well and cut into 3/4" pieces
coarse sea salt and freshly ground pepper
2 T. white-wine vinegar
1 t. Dijon mustard
3 T. extra-virgin olive oil
3 oz. crumbled goat cheese (1/2 c.)
1 celery stalk, finely chopped
1 small shallot, finely chopped
2 T. finely chopped fresh flat-leaf parsley
Cover potatoes with water in a medium saucepan; season with salt, and bring to a boil. Reduce heat, and simmer until tender, 10-12 minutes. Drain, reserving 1 T. cooking liquid. Let potatoes cool for 5 minutes.
Whisk together vinegar, mustard, and reserved cooking liquid. Add oil in a slow, steady stream, whisking constantly until emulsified.
Transfer potatoes to a bowl, and drizzle with vinaigrette. Gently stir in goat cheese, celery, shallot, and parsley. Season with salt and pepper.