Creamy Two-Potato Salad

Directions

1. 1
   In 5- to 6-quart saucepot, place red potatoes and enough water to cover by 1 inch; heat to boiling over high heat.
2. 2
   Reduce heat to low and simmer 2 minutes.
3. 3
   Stir in sweet potatoes; heat to boiling over high heat.
4. 4
   Reduce heat to low; cover and simmer 8 to 10 minutes or until potatoes are just fork-tender.
5. 5
   Meanwhile, in large bowl, with wire whisk, mix vinegar, mustard, salt, and pepper.
6. 6
   Drain potatoes well.
7. 7
   While hot, add potatoes to dressing in bowl; gently stir with rubber spatula until evenly coated.
8. 8
   Let stand until cool.
9. 9
   In small bowl, whisk mayonnaise and milk until smooth.
10. 10
    Add mayonnaise mixture, celery, onion, and parsley to potato mixture; gently stir with rubber spatula until potatoes are well coated.
11. 11
    Serve warm, or cover and refrigerate until ready to serve.