About half of a bag of pinto beans, cooked (overnight in the crock pot works just fine), drained.
Mash them up and add a packet of onion soup mix (I checked. It does not contain beef). Add some oats, and some flax seed meal that have been turned to slime in a bit of boiling water (egg substitute). Stir well.
Form into patties and roll gently in corn meal.
Bake for a while until they smell good.
Make a burger in the usual way. These taste very good. Almost....meaty.