Delicious! Nothing more to say except do not leave out the celery seed!
Source: Cook’s Illustrated
2 pounds russet potatoes (3 to 4 medium, peeled and cut into 3/4 inch cubes)
2 Tbs. distilled white vinegar
1 medium celery rib, chopped fine (about 1/2 cup)
2 Tbs minced red onion
3 Tbs sweet pickle relish
1/2 cup mayo
3/4 tsp. dry mustard
3/4 tsp. celery seed
2 Tbs. minced fresh parsley leaves
1/4 tsp. ground black pepper
2 large hard-cooked eggs, peeled and cut into 1/4 inch cubes (optional)
1. Place potatoes in large saucepan and add cold water to cover by 1 inch. Bring to boil over medium-high heat; add 1 Tbs. salt, reduce heat to medium, and summer, stirring once or twice, until potatoes are just tender when tasted, about 8 minutes.
2. Drain potatoes and transfer to large bowl. Add vinegar and, using rubber spatula, toss gently to combine. Let stand until potatoes are just warm, about 20 minutes.
3. Meanwhile, in small bowl, stir together celery, onion, pickle relish, mayo, dry mustard, celery seed, parsley, pepper, and 1/2 tsp. salt. Using rubber spatula, gently fold dressing and eggs, if using, into potatoes. Cover with plastic wrap and refrigerate until chilled, about 1 hour; serve.