Burger King was sued on Monday by a vegan customer who accused the fast-food chain of contaminating its meatless “Impossible” Whoppers by cooking them on the same grills as its traditional meat burgers. In a proposed class action, Phillip Williams said he bought an Impossible Whopper, a plant-based alternative to Burger King’s regular Whopper, at an Atlanta drive-through, and would not have paid a premium price had he known the cooking would leave it “coated in meat by-products.” The lawsuit filed in Miami federal court seeks damages for all U.S. purchasers of the Impossible Whopper, and an injunction requiring Burger...