1. Heat oven to 400 degrees F.
2. Toss potatoes with oil in roasting pan until potatoes are well coated. Sprinkle with rosemary, garlic, salt and pepper; toss until potatoes are well coated.
3. Bake in 400 degree F oven for about 15 minutes. Lower the oven to 350 degrees F. Bake for 20 minutes or until the potatoes are cooked through but still somewhat firm; stir the potatoes during the baking.
4. Transfer the roasting pan to a wire rack and let the potatoes cool until warm.
5. Place potato halves, flat side up, on a serving platter. Dollop each potato half with a teaspoon of sour cream and a teaspoon of caviar. Serve at once. Makes about 3-1/2 dozen potato halves.