Found this shop by chance on Nara Explorer, an English-based tourist magazine produced by the volunteers (see http://www.naraexplorer.jp/dining/uo.html),
Serves a single vegetarian curry dish that is delicious and pretty spicy by Japanese standards.
Good enough I brought my wife back for a second round in two days.
15 min. walk from JR Nara Sta. along Sanjo Street, enter the Mochiidono Center Arcade and the shop is on the leftPros: Great vegetarian curry, Small but cosy
Cons: Just one vegetarian dish