Step 1: Wash and cube the potatoes. Place them in a large pot and cover with cold water by about an inch. Add a generous pinch of salt to the water.
Step 2: Bring the pot to a boil over high heat, then reduce the heat to a simmer. Cook the potatoes until they are fork-tender but still hold their shape (about 10-15 minutes). Drain well in a colander and let them steam dry for a few minutes.
Step 3: While potatoes cook, prepare the dressing. In a large bowl, whisk together the mayonnaise, apple cider vinegar, Dijon mustard, sugar, salt, and black pepper until smooth. Taste and adjust seasoning as desired.
Step 4: Add the still-warm, drained potatoes to the bowl with the dressing. Gently fold until all potatoes are evenly coated. Cover and refrigerate for at least 30 minutes, or ideally 2-3 hours, to allow flavors to meld and potatoes to cool completely.
Step 5: Once chilled, stir in the finely chopped celery, red onion, and fresh dill. Gently fold to combine.
Step 6: Taste the dill potato salad recipe again and adjust seasonings if necessary. Serve chilled and enjoy!