Put the oil in a frying pan over medium heat, then add the onion and garlic and cook for 5 minutes or so, until soft and translucent. Put the cooked onions into a food processor and blitz briefly to get a rough paste.
Put the venison in a large bowl with the tomato ketchup, Dijon mustard, egg, breadcrumbs, Worcestershire sauce, cranberry sauce, salt and black p