Las Iguanas is a chain of restaurants serving South American style food and drinks with a separate vegan menu. There are some very nice options including fajitas, burritos, jackfruit curry, guacamole, patatas bravas and sorbet for pudding. There's a good range of drinks including cocktails (years ago I had my first ever caipirinha here).
They cope very well with large groups so it's a good place for birthday celebrations and workplace outings.
The restaurant is centrally located just off the Old Market Square. To save time, ask for the vegan menu when you go in, as you are shown to your table.