In an attempt to visit all the food carts near my work this summer, one of the places I tried was Sausage a Trois, owned by the same person who owns Fresh Local Wild, Chef Wolfe.
The special thing about these sausages is how they are cooked three ways...thus the name. They are steamed and smoked beforehand, and then grilled at the time you order them.
The beef they use is certified organic, as the other meats they offer, pork and lamb are all ethically raised as well. I love the little char they get onto the bun. Topped with mustard, ketchup or sriracha, these are really good. You can really taste the flavour imparted by the smoker...and for $5, it's an awesome deal!