Calçotada is the most traditional way to eat onions with strong connotations of celebration and gathering . Valls , the city which is native calçotada held in late January from 1982 calçotada most popular renown. Calçotades are usually from late winter until March or early April , depending on the season . The starter menu are typical calçotada onions (usually between 10 and 20 per person) , served on tiles to maintain its temperature, with typical sauce that accompanies the salvitxada or romesco . After usually eat toast with grilled meat accompanied by wine or champagne . Because onions are served as they come out of the grill and you peel them and dip them in the sauce , it is common to wear a bib to avoid staining clothes. Historia Even though Valleys and county calçotada held since the early twentieth century , the meal began to become popular from the middle of last century. Thus , over the years, has become a delicacy calçotada typical Alt Camp and has also spread to neighboring regions (Tarragona , Costa Dorada , Penedès and Conca de Barbera ) . Today this tradition is much more widespread and reaches even to Mallorca.