Cut a small slice from the bottom of each potato so that it sits flat.
Working from one end of the potato to the other, cut thin slits, slicing almost to the bottom but not completely through. These cuts need not be wide; the potatoes will fan out as they bake.
Immediately place the potatoes in cold water after slicing to keep them from discoloring.
In a shallow bowl, mix the olive oil, salt and pepper, rosemary, thyme, and garlic. Drain and dry the potatoes, then roll the potatoes one at a time in the olive oil mixture to coat.
Arrange the potatoes in a baking dish and pour any excess seasoned oil over them.
Bake for 45 to 60 minutes, or until crispy and brown on top.