Place the cubed potatoes in a large pot and cover with cold water by about 1 inch. Add 1 teaspoon of salt to the water.
Bring the water to a boil over medium-high heat, then reduce to a simmer. Cook the potatoes until they're fork-tender but still hold their shape, about 8-10 minutes.
While the potatoes are cooking, prepare the dressing. In a large bowl, whisk together the olive oil, apple cider vinegar, Dijon mustard, honey, 1/2 teaspoon salt, and 1/4 teaspoon freshly ground black pepper until well emulsified.
Once the potatoes are cooked, drain them thoroughly in a colander. Let them steam dry for about 2 minutes.
While the potatoes are still warm, gently add them to the bowl with the dressing.
Gently fold the potatoes with the dressing until every piece is well coated. Be careful not to break the potatoes.
Add the chopped parsley and sliced green onions, along with any optional add-ins you've chosen. Fold everything together gently until well combined.
Taste and adjust the seasoning with additional salt and pepper if needed.
Serve the potato salad while still warm, or allow it to come to room temperature before serving.
