Not wanting to waste any precious eating opportunity on poor food, I did a little research before we arrived in Barcelona. The first place we eat was one of the places recommended in a Telegraph article

Lúzia
A modern but cosy little restaurant just a couple metres down a side street off the bustling La Rambla. There wasn’t a large amount of authentic Spanish food on the menu, in fact there wasn’t a whole lot on it at all, but we decided to both order the beef sandwich – as recommended.
It wasn’t the biggest sandwich I’ve ever had, but I have to admit it was probably the best. There was a pretty generous filling of roast beef, gherkins, mortadella and mustard in slices of lightly toasted brown bread.
If you’re after a hearty meal then this isn’t it, but it does suit for a light lunchtime snack, even if it is a little pricey at €11. It was a tasty sandwich, but I’m not sure I would recommend going out of your way to try out Lúzia.

Rita Blue
Having wandered all the way to the beach and then back up La Rambla, we were getting to be ravenous again. We were nearly tempted into one of the many street seating, picture-filled menu, restaurants on La Rambla.
We resisted and took a turn up a side street leading us to Placa Sant Agusti. There were stumbled upon Rita Blue.
Seated outside in the shadow of the church building it was a perfect, quiet corner of the city. We didn’t look at the menu and just ordered the Paella advertised on the board.
There was quite a bit of a wait for be food, but a delicious looking paella for two eventually arrived.
Overall it was a tasty meal, though it was very, very salty. A slightly odd little place, but worth a go. And the cocktails looked brilliant, though sadly we didn’t try one.