Chop the potatoes into 1/2 inch pieces and steam them in a large pot until tender but not mushy (about 10 minutes). I use a steamer basket in a large pot filled with boiling water about 2 inches deep.
Chop the scallions and celery, then place them in a large bowl. Add the cooked potatoes and stir them gently with the vegetables.
Mix together the mayonnaise and red wine vinegar.
Pour the dressing over the potatoes while they're still warm.
Add salt and pepper to taste and garnish with fresh chives. Serve warm or cold.