This new restaurant concept is growing quickly but trades at a steep valuation.Investors love a growth story, especially one in its early stages. So it is no surprise to see Wall Street fawning over restaurant upstart Cava (CAVA 0.23%).The Mediterranean fast-casual concept that has modeled itself after the likes of Chipotle and Sweetgreen has seen its stock soar more than 100% in less than six months to start 2024. It is growing locations quickly and building an ardent fan base around the country.What's nex ...