Pressure cook the drained, rinsed kidney beans in salted water. Once cooked, drain well.
Rinse and cook the millet in plenty of lightly salted water. Once its ready, in about 10-12 minutes, drain it and rinse it well with cold water. Drain again and set aside.
Saute the onions and garlic in 1 Tbsp of olive oil for about 5 minutes, till slightly softened. Add the chopped tomatoes, chillies, drained millet, Sambal Olek and salt & pepper to taste. Let it all cook for another 5 minutes. Take it off the heat. Mix in the lemon juice and parsley. Taste and adjust seasoning. Cool this mixture for 10 -15 minutes.
Meanwhile, place the drained kidney beans in a large bowl and mash roughly with a fork. Add the cooled millet mixture and mix it all together very well. We are looking for a chunky sort of a mixture here, so don't worry about getting everything smooth and pasty. Taste and adjust for seasoning again.
If the mixture seems a little wet, add some polenta or semolina, to bind it together. It will be still be a little sticky. Shape into 10-12 patties.
Sprinkle some polenta/ semolina on a tray and place the patties on top. Sprinkle some more polenta on top. Refrigerate these for a couple of hours or until you are ready to eat. This is important, otherwise the patties will crumble in the pan as they are very soft.
Preheat a large skillet, add 1 tbsp of olive oil and carefully place the patties in the pan. Cook for 6-8 minutes each side, or until browned and crispy on both sides.
Assemble the burgers :
Split each burger bun in half, smear with mayonnaise, mustard. Top with lettuce, tomatoes, onions, pickles and the burger patty. Enjoy!!