From Silicon Valley to SoMa, the Bay Area is packed with blockbuster companies that were built on little more than a good idea. But there’s only one that was built on a condiment. Three years ago, Hampton Creek’s Just Mayo, which swaps a protein derived from Canadian yellow peas for the eggs that help emulsify oil into sandwich-spreadable goodness, appeared in Whole Foods (and, later, Walmart and Kroger) stores across the nation. Among an increasingly…