Lunch time and you are in a hurry? Keen on a sandwich/bagel? Don't know what to put inside? Want everything on your sandwich? Magasand, Travesia de San Mateo 16 and Columela 4, can make you the perfect one for you and they are healthy too. They have a counter with different ingredients and then you just pick what you want.
They have also salads where you can choose your ingredients and very very good desserts.
Picture borrowed from here.