Pere Sirvent strode into the food market in the Sants neighborhood of Barcelona on a recent morning and looked around with satisfaction. Under the vaulted ceiling of the 1913 building, which reopened in late spring after a four-year, 10-million-euro renovation, the fishmongers arranged ruddy wedges of tuna on crushed ice. Produce sellers bagged glistening cherries. At a large stall offering prepared foods, customers eyed the truita de patates, a crustless quiche made with potatoes.