Find these bitter greens - cultivated rather than wild - at Whole Foods and some Middle Eastern sources listed in Markets. If you pick wild dandelions, make sure you do it before they bloom, don't do it in a dog park and do wash them extremely well before using.

Chef Hisao Abe, who owns Kotobuki on MacArthur Boulevard, learned the art of sushi-making after years of watching, sniffing, tasting.