Place the whole, unpeeled Yukon Gold potatoes in a large pot and cover with cold water by about an inch. Add 1 tablespoon of salt to the water. Bring to a boil over high heat, then reduce heat to medium-low and simmer until the potatoes are fork-tender, about 15-20 minutes depending on their size. Be careful not to overcook them, or they will become mushy.

Drain the potatoes thoroughly in a colander and let them cool for about 10-15 minutes until they are cool enough to handle but still warm. While still warm, peel the potatoes (the skins should slip off easily) and cut them into 3/4-inch to 1-inch cubes. Place the cut potatoes in a large mixing bowl.

While the potatoes are cooking and cooling, prepare the dressing. In a small mixing bowl, whisk together the mayonnaise, Dijon mustard, white wine vinegar, granulated sugar (if using), salt, and black pepper until smooth and well combined.

To the bowl with the warm, cubed potatoes, add the finely diced celery, finely diced red onion, chopped fresh dill, and chopped fresh parsley.

Pour the creamy Dijon dressing over the potato mixture. Gently fold everything together with a rubber spatula until the potatoes and vegetables are evenly coated with the dressing. Be careful not to mash the potatoes.

Taste and adjust seasonings if necessary, adding more salt, pepper, or vinegar to your preference.

Cover the bowl with plastic wrap and refrigerate for at least 2 hours, or preferably overnight, to allow the flavors to meld. The salad will taste even better the next day.

Before serving, give the potato salad a gentle stir. Garnish with additional fresh dill if desired.