Jared Zimmerman/FlickrStick a fork in it.Mission Burger, our heart is broken, too! Ever since we tried the vegan burger served at Duc Loi Market (2200 Mission at 18th St.), we've talked it up as one of the best burgers around. Sad to read that the vegan burger is being canceled due to a deep-fryer cross contamination complaint that led to what Mission Burger describes on its Yelp page as a broken heart. Unfortunately, yes we will cancel it pretty soon because it takes a lot of work to mak