Vinegary potato salad with dill and scallions

This is a summer staple (taught to me by a kind and unhappy man who subsequently drank himself to death. His salad lives on). The vinegar works surprisingly well with the strongly flavoured dill and green onions.  Add the dressing while the potatoes are still warm, but not hot.

2 pounds small red-skinned potatoes, halved
1/4 cup good white wine vinegar
1/2 teaspoon salt
1 teaspoon sugar
Copious amounts of black pepper
1/3 cup extra virgin olive oil
1 bunch scallions (6-8 onions), cleaned and chopped (greens, too)
1 bunch fresh dill, chopped (yield = 3/4 cup)

Cook the potatoes in boiling water to which you've added some salt. While they are cooking, thoroughly whisk together the vinegar, salt, sugar, pepper and oil. Drain potatoes when just-cooked. In a large bowl add the dressing to the hot potatoes and stir gently. Add the dill and scallions and mix well. I use my hands in order not to break the potatoes too much.

Lick fingers.

This is good now, warm, or later, cold.