Roe is the ripe egg mass of a fish, salt-cured and eaten as tiny, glistening beads that burst with a briny pop of the sea. It runs from the big amber pearls of salmon (ikura) down to the crunchy, coloured specks of flying-fish tobiko and the finer, cheaper capelin masago that stud a sushi roll. Milder, softer and far more affordable than sturgeon caviar, these roes bring a saline, faintly sweet, mineral-marine flavour and a signature snap-and-ooze texture that make them a garnish, a filling and a luxury in one.