Second Avenue Deli's Potato Salad adapted

3 pounds red potatoes
3/4 cup finely chopped onions
3/8 cup vinegar
2 tablespoons sugar
1 1/2 teaspoons salt
1/4 teaspoon pepper
3/4 cup mayonnaise
1/4 cup shredded carrot

1. Boil potatoes until firm, but soft. Drain and take off skin. Cut into chunks.
2. While potatoes are still warm, add onion.
3. Make a vinaigrette using vinegar, sugar, salt and pepper. Mix in with warm potatoes.
4. Gently stir in mayonnaise and carrot. Chill.