Grammy'S German Potato Salad - cooking recipe

Ingredients

8 white potatoes, peeled and cut into cubes
1 large onion, chopped
2 teaspoons white sugar
1/2 teaspoon dry mustard
1/2 teaspoon salt
1/4 cup cider vinegar, divided
1 pinch ground black pepper
1/4 cup vegetable oil

Preparation

Place potatoes into a large pot and cover with salted water; bring to a boil. Reduce heat to medium-low and simmer until just tender, about 15 minutes; drain.
Put potatoes into a large bowl; add onion and stir.
Mix sugar, mustard, and salt together in a bowl. Stir just enough vinegar into the sugar mixture to form a paste; season with black pepper.
Whisk remaining vinegar and vegetable oil together in a separate bowl until smooth; stream into bowl with the paste, whisking continually to incorporate. Pour the dressing over the potato and onion mixture.
Cover the bowl with plastic wrap and let salad cool slightly, 5 to 10 minutes.