Preheat the oven to 400 degrees F (200 degrees C). Line a baking dish or rimmed sheet with foil.
Place halved potatoes in a large resealable plastic bag. Add olive oil and Italian dressing mix, seal bag, and shake until all potatoes are coated evenly. Transfer to the prepared baking dish.
Roast in the preheated oven until tender, flipping potatoes halfway through cooking time, about 30 minutes.