The calçotada brings entire towns together around an unusually sweet local onion – the calçot – blackened over a fire of grapevine clippings, served with a variation on romesco sauce and washed down with a jet of wine from a Catalonian porró.

These neighbourhood festivals pair heaps of grill-charred calçots with barbecued meats, blackened hazelnuts, olives and red or white wine. Here is everything you need to bring this onion party home.

The Onion

The calçot is a giant Catalonian scallion grown from seed and harvested, then allowed to germinate again before being trimmed and replanted in trenches. The growing process can take up to 18 months and results in a concentration of flavours and an unusual size, often as big as a leek. As the calçots grow, earth is piled up around their stalks like with celery or leeks. This makes the lower stems look like white socks or boots, which is how they get their name: from the Catalonian verb calçar, to put on shoes.

Short of building your own calçot planter and planning well in advance, those of us in Canada should look for scallions that are thicker and juicier than usual, or the bulbed variety often found during spring.

The Grill

Calçots are slowly blackened over coals before being wrapped in newspaper to steam; this renders the flesh tender and makes it easy to peel the charred outer layers.

The Sauce

Every restaurant and household has its own recipe for salsa de calçots, or salvitxada, a less bitter variation on romesco that calls for ñora peppers instead of choriceros. It is delicious with all grilled foods.

If You Go

To take part in a genuine calçotada, you’ll have to visit Catalonia between late January and April. Valls, a mountain town north of Tarragona, is the capital of calçots.