not familiar with those restaurants but this has been a family favorite for generations. Although I add more vinegar (close to a cup between the 3 vinegars) and I seldom use the sugar mother put in (particularly if I have vidalia or mayan onion). My sister prefers a little celery seed but here is our recipe
German Potato Salad
2 lbs unpeeled potatoes
6 slices of bacon cut in small pieces
½ cup chopped onion
2 tsp sugar
2 tsp salt
¼ tsp pepper
¼ cup cider vinegar
¼ cup red wine vinegar
1 or 2 Tbl balsamic vinegar - optional
• Boil potatoes until fork tender (20-30 min). Salt the water.
• Drain potatoes and cool slightly. Peel and cut potatoes into cubes about an inch big.
• Cook bacon in skillet over medium heat until crisp. Remove from skillet and drain on paper towels.
• Cook onion in the bacon drippings, add sugar, salt and pepper and cook until carmelized and tender.
• Stir in vinegars.
• Stir in potatoes.
• Crumble bacon into pan
• Keep the heat low until you are ready to serve so the potatoes don’t burn.
As much as I've disliked Sally Sherman salads, your reference to that brand leads me to believe you prefer a little sweetness in your German potato salad.
My recipe differs a little from the good, quick, easy one that masha posted, above.
For 2 pounds of potatoes, make a salad sauce of 2 cups oil (if using olive oil *don't* use extra-virgin), scant 1/4 cup cider vinegar, scant 1/4 cup white vinegar, 1/4 cup Grey Poupon dijon mustard, a teaspoon of honey, and a teaspoon of white sugar.
Cut a big, fat sweet onion (a Vidalia or Chef's onion preferred) in half, peel and thinly slice the halves. Let the onion sit in the dressing, preferably for a day. A little dill weed/dill seed may be added at this time. Some prefer to use caraway seeds.
I like to peel the potatoes first (yeah, it's work) and slice/cube them to the shape I want in the salad (we like 1/4" thick half-moon slices). Then I boil the potatoes in water with a quartered onion, a little salt and lots of bay leaves. Drain the potatoes when done to the texture you like 'em.
While the potatoes are still very warm, pour the dressing/onion mixture over them. Cool to room temperature, or serve warm. Garnish with finely minced flat parsley.
I'm not familiar with the particular restaurants you name or a "New England" style of German potato salad, so this response may not be what you are looking for but...
My German potato salad recipe is very basic.
Boil whole red potatoes if they are small, or halve or quarter if larger, in their jackets for about 10 minutes until tender.
Allow to cool enough so that you can handle them. Then slice them somewhat thick (about 1/4 in), leaving the skin on.
Add some diced red onions, and then toss with a dressing made of dijon mustard, 1 part cider vinegar to 3 parts olive oil, salt & pepper.
Name: GERMAN Potato Salad
Key Ingredient: potato
Temperature: room, warm
Comments: This can be made in advance and sit at room temp for 3 hours. If not warm enough at serving time, nuke for 2 minutes.
2 lbs red potatoes (unpeeled, quartered)
8 strips bacon, cut into 1/2 inch pieces
1 large onion, chopped
1/2 teaspoon sugar
1/2 cup white vinegar
1 tablespoon whole grain German mustard
1/4 teaspoon pepper
1/2 cup chopped Italian parsley, chopped
Boil potatoes until done, but not mushy. Reserve 1/2 cup potato cooking water. Drain and keep warm.
Cook bacon in large skillet until crisp, remove to a paper towel.
Keep 1/4 cup of bacon grease and add onion to skillet and cook until soft.
Add sugar and stir until dissolved.
Add vinegar and potato water and bring to simmer and cook until mixture is reduced to about 1 cup.
Remove from heat and whisk in mustard and pepper.
Add potatoes, parsley and bacon to skillet and toss to combine.
Season with coarse salt.