Transfer the potato chunks to a large bowl and drizzle with vinegar. Add mayonnaise, green onions, parsley, dill, salt, oregano, and garlic powder. Toss well to combine until the potatoes are evenly coated, then taste and adjust salt as needed.
1/4 cup red wine vinegar, 1 cup mayonnaise, 1/2 cup chopped green onions, 1/4 cup chopped fresh parsley, 1/4 cup chopped fresh dill, 1 teaspoon coarse kosher salt, 1 1/2 teaspoon dried oregano, 1/2 teaspoon garlic powder