From Cook’s Country
2 tbsp. sugar
1 cucumber, peeled, seeded, and cut into ¼-inch slices
1 cup white vinegar
½ tsp. dried dill
salt and pepper
3 pounds small red potatoes, scrubbed and sliced ¼ inch thick
8 slices bacon, chopped
1 onion, minced
¼ cup olive oil
¼ cup coarse grain mustard
¼ cup chopped fresh parsley
Stir sugar, cucumber, ½ cup vinegar, dill, and ½ tsp, salt together in a bowl; set aside.
Bring potatoes, remaining vinegar, 1 tbsp. salt, and 8 cups water to a boil in a large pot. Reduce heat to medium and simmer until potatoes are just tender, 10-15 minutes. Drain potatoes and return to pot.
Meanwhile, fry bacon in large skillet over medium heat, stirring occasionally, until brown and crisp, 8 minutes. With slotted spoon, transfer bacon to paper towel-lined plate; pour off and discard all but 2 tbsp. bacon grease. Add onion and add oil to skillet and cook, stirring occasionally, over medium heat until onion is softened and beginning to brown, about 4 minutes.
Drain cucumbers and reserve the juice. Whisk cucumber juice, mustard, and 1 tsp. pepper into skillet; bring to a simmer. Pour dressing over warm potatoes, stir to combine, and let sit until slightly cooled and potatoes have absorbed dressing, about 10 minutes.