Bring a large pot of salted water to a boil and cook potatoes until fork-tender, about 12–15 minutes.
In the last 3 minutes of cooking, add the asparagus to the pot.
Drain vegetables and transfer to a large mixing bowl.
In a small bowl, whisk together olive oil, white wine vinegar, Dijon mustard, salt, and pepper.
Pour dressing over the potatoes and asparagus; toss gently to coat.
Sprinkle with chopped parsley before serving.