This place is on the map in the Lonely Planet guides and not far from the historical old town. It is easy to find. I ate here twice and the main dishes were different each time. It is nothing fancy but it offers a decent buffet style lunch and you can choose the vegan options only if you don't want food containing cheese. They also have vegan empanadas which are good and cheap. I recommend stocking up on them for bus rides or snacks later in the day.