Burger 21 is a three-year-old fast-casual “better burger” concept that has taken lessons from rivals’ earlier efforts and aims for steady franchise growth. The menu includes 10 beef and 10 non-beef burgers, as well as one rotating monthly special. The chain, created by the company that manages The Melting Pot restaurants, has seven locations and expects to end the year with about a dozen in six states. Read the FastCasual.com story here.