Potatoes and bacon are a delicious combo in this salad.
Add potatoes and 2 tablespoons salt to a large pot of cold water. Bring to a boil; boil potatoes until almost fork tender. Drain.
Cook bacon in skillet until crisp, 5 minutes. Remove bacon, crumble, and set aside. Pour off all but 2 tablespoons fat.
Return skillet to heat; add onions and cook until soft, 3 to 5 minutes. Add 5 tablespoons oil, vinegar, and sugar; cook, stirring until sugar dissolves, 3 to 5 minutes. Add 1 1/2 teaspoons salt and 1/4 teaspoon pepper.
Heat grill to medium hot. Slice potatoes in half; toss with remaining 3 tablespoons oil, 1 1/2 teaspoons salt, and 1/2 teaspoon pepper. Grill potatoes until crisp and cooked through, 3 to 4 minutes per side. Return potatoes to bowl. Add dressing and bacon; toss. Serve warm or at room temperature.