1. Rinse and scrub potatoes, then slice into ¼-inch slices. Add to a large saucepan and cover with water. Add a healthy dash of salt (for flavor) and bring to a boil. Once boiling, reduce heat slightly (to medium/high) and continue cooking for 10-15 minutes or until the potatoes are easily pierced with a knife.
2. Drain potatoes and rinse with cool water. Then once mostly dry, add to a large serving bowl. Season with a dash of salt and black pepper and apple cider vinegar. Set aside.
3. While potatoes are cooking, prepare dressing. Add mustard, garlic, salt, pepper, red wine vinegar, and apple cider vinegar to a mixing bowl and whisk to combine. Then, while continuing to whisk, slowly stream in the olive oil to emulsify the oil and vinegar. Add the dill and whisk once more.
4. Add the dressing to the potatoes along with the green onion and parsley and toss to combine. Taste the potato salad and adjust salt and pepper to taste. It’s now ready to enjoy, but it also soaks in more of the flavor of the dressing the longer it sits.
5. Serve warm, chilled, or room temperature.