Preheat oven to 400 degrees.Quarter or half all the potatoes, depending on size. You want them all to be relatively the same size so they cook evenly.In a large bowl, combine prepared potatoes, broth, vinegar, garlic, and rosemary; season with salt and pepper. Toss to combine and pour the mixture into a shallow 2 quart baking dish.
Bake until potatoes are tender and liquid is reduced to a syrupy consistency, about 1 3/4 hours, tossing two or three times during baking.