Although pupusas have been delighting the residents of El Salvador for a few thousand years, these savory noshes only arrived here in the 1980s, when émigrés from the country's civil war introduced the pleasures of stuffed and grilled masa to the Mission District. Now the town is blessed with a plethora of pupuserias where loroco fiends can satisfy their cravings with equanimity. Our favorite is Elsy's, a sunny if nondescript hole-in-the-wall spot where a skilled artisan stands in the window preparing pupusas to order. She takes a ball of dough made from corn and rice flour, works in whatever fillings you desire (cheese, shredded pork, refried beans, squash or the aforementioned loroco, a sharp, tangy nasturtium-like flower native to the old country), flattens it and grills it until crisp and hot, and serves it with curtido, a peppery slaw as imperative to the pupusa experience as mustard is to the hot dog. The result is a crunchy, oozing, plate-sized bit of heaven that satisfies belly and soul alike.