alliaceae allium allium-cepa Amaryllidaceae brown-onions bulbs circular crisp cultivars donut-onions doughnut-onions edible firm flat flat-top flattened flavonoids flavor flavour food healthy Italian-heirloom juicy layers medicinal mild-aroma nutritious odor odour onion papery-skin produce pungent raw rings round salad-vegetable saucer-shaped-bulbs shape skins soup-vegetable squat stir-fry-vegetable tangy tasty thin variety vegetable white shooting-onion