In Juicy Jones you get really good, tasty and healthy food without any animal products.
To be honest: I am not vegan, not even vegetarian.. but I do love this restaurant. A vegan friend invited me one day to go there and try it..I was deeply surprised how good and tasty vegan food can be.
They also offer really good fruit juices, smoothies and shakes - delicioso drinks, which give you an energy boost.
You can enjoy the Menu del Dia, which gives you a choice of appetizer, main course, dessert, and beverage, for a very reasonable price of 8,50 €. You should definitely try the "Thali" there, one of the best I have ever had.
Juicy Jones has a really funky, kind of "Gaudi-esque" design inside, which seems a bit psychedelic. Basically the walls are as bright and colorful as a nicely filled fruitbowl. So sometimes it might be a bit difficult to concentrate on the menu without getting distracted by the design of the restaurant. The staff is really friendly and you feel very welcome there.
You can find this vegan spot just off the Ramblas, the closest Metro station is Liceu, the green line #3. Here a little video of Juicy Jones.. also interesting when you are not speaking spanish ;)
Here is a little guide and some useful spanish phrases for you to survive without the piglegs in Barcelona: click here
C/ Cardenal Casañas 7, Ciutat Vella (at Plaza de Pi)
Tel. 933024330 credits for pics: http://www.veggieplaces.co.uk (also a good place to check some vegetarian/vegan restaurants ;))