The popular pop-up restaurant Mission St. Foods – which hosts guest chefs who cook dinners Thursdays and Saturdays at the Lung Shan Restaurant (2234 Mission St.) – has started flipping burgers. Everyday except Thursday, they are now offering 1/3 lb. burgers ($8) and vegan burgers ($7) with fries ($2) from the meat counter of Vietnamese supermarket Duc Loi (22000 Mission St., at 18th St.). The signature patty, fashioned out of granulated meat in the style of Heston Blumenthal's, is topped with caper aioli and grilled onions, and is accompanied by a side of grilled hot chile (noon until supplies run out; $1 of each purchase goes to the San Francisco Food Bank).