Tidy eaters need not apply to the "smashed onion burger" at Sketch.
There are fancier options at this funky Fishtown burger atelier, where owners Megan Roberts and Phyllis Farquhar serve an extensive list of serious dry-rubbed patties with homemade toppings, from a Kobe burger worth its pedigree (best with wasabi sauce) to a house-veggie burger and Dr Pepper-braised pork.
But there is something so amazingly primal about the smashed onion burger, I simply can't resist. It involves pressing a fistful of raw onions into one side of the thick, 8-ounce patty, then grilling them hard - until the lacy, caramelized onions leave their heat-charred tattoo on the juicy meat.