Wash and dice the 3 pounds of red potatoes into evenly sized bite-sized pieces. In a large mixing bowl, toss the potatoes with 2 tablespoons olive oil, 1 teaspoon garlic salt, and 1 tablespoon chopped fresh rosemary until evenly coated.
Line a baking dish with foil for easy clean-up.
Spread the potatoes out onto the pan and bake for 40-45 minutes until the potatoes are slightly golden brown and fork tender.