Chop the onion, mix with the meat, breadcrumbs, and 4 tablespoon cranberries. Then add the egg. If necessary, add enough breadcrumbs to form burgers. Season with salt and pepper.
Form four large, flat burgers from the mixture, approx. 1.5-2 cm thick. Put in a cold place and preheat the oven to 200 ° C. When the oven is ready, brush the burgers with oil on both sides, place them on a rack lined with baking paper, and fry for 10-15 minutes on each side.
Cover the rolls with lettuce, tomato slices, cranberries, and burgers.