Ravioli are small pasta parcels, usually square, with a filling sealed inside — meat, cheese, spinach, or a mix. You boil them and often put sauce on top. English borrowed the Italian word and mostly treats it as a plural already, so one piece or a plateful can both be ravioli; a careful cook may say raviolo for one, but few English speakers bother. Though actually, restaurants do not always keep the square, and the filling is not always meat or cheese — pumpkin, mushroom, and seafood all exist. In Taiwan they sit next to dumplings in people’s minds, which is a fair first picture, even if the pasta dough and the sauce feel different from jiaozi.