This Streeterville burger and shake joint's mission is simple: Give Michigan Avenue workers and weary shoppers the quick, easy lunches they desire. Created by the Lettuce Entertain You crew and located just east of the Mag Mile adjacent to LEYE's high-end Tru, M Burger is a mostly counter service spot (it seats only eight) where you can grab a hamburger, cheeseburger or chicken sandwich for surprisingly little money. (Everything on the menu is less than $5.) The concise lineup includes a few extras, such as fries, shakes (chocolate, vanilla, strawberry and a flavor-of-the-month) and a single vegetable sandwich, the Nurse Betty, named for a well-known nurse at nearby Northwestern Hospital. But for the most part, this place focuses on one thing: simple burgers that aren’t so greasy and filling that you’ll need a nap 20 minutes after the last bite.