Chop the vegetables finely. Choose very flavorful ones such as those named above, carrots can also be considered, but the total volume of vegetables should be about half the volume of beans.
Cook the vegetables in one tbs of oil on a low flame to slowly wilt and soften the vegetables.
Meanwhile, boil the rice or barley in water. And also crush the beans.
Add the cooked vegetables and the barley (or rice) to the bowl of mashed beans.
Add the ketchup, mustard, soy sauce, salt and pepper, and blended egg. 0r leave out the egg if you prefer a vegan version. If going vegan, though, be sure to do the kneading step below.
Knead the mixture with the dome to stretch the proteins and make the mixture hold together better.
Form into burgers.
Bake them on an oiled baking sheet or fry in a pan lightly coated with oil.