Preheat oven to 400°F. Arrange potatoes in a single layer in a shallow rectangular or oval 9x1 3" pan. Pour oil around to make a 3/4" deep layer. Stir in onion-lemon juice mixture and top with about dried rosemary. Bake in 400° F oven, shaking occasionally to rotate potatoes in oil, until the largest give readily when pressed, 25-40 minutes. Serve garnished with additional dried rosemary. Salt to taste. Serves 8.