Directions

1. Bring a large, covered pot of salted water to a boil over high heat. Add potatoes and boil with the lid ajar until you can easily pierce them with a knife, 15-20 minutes. Drain potatoes and let cool slightly until you can handle them.
2. Meanwhile, in a large bowl, whisk together parsley, olive oil, shallot, mustard, vinegar, sugar if using, 1/2 tsp. salt, and the pepper.
3. Cut potatoes into bite-size pieces. Add to the vinaigrette while it’s still warm, and gently toss to coat. Let salad cool to room temperature, about 35 minutes, stirring occasionally. Season to taste with more salt and pepper and a splash more vinegar if you like.
4. Fold arugula into salad.