Walla Walla onions are the official state vegetable of Washington state. But there’s a special secret to these onions’ deliciousness. The reason WallaWalla onions taste amazing is the amazing prime farmland soils in Walla Walla. Some of the richest most fertile soils on the planet grow onions that can actually be eaten raw with a smile. For more info on the growth of Walla Walla sweet onions, take a look at this History Link article.