Heat the oil In a large stew pot, on a medium heat. When hot add the onions and garlic. Cook for 4-5 minutes until onions are softened.
Add the eggplant and saute gently for a further 5 minutes.
Add the tomatoes and cook for a further 1-2 minutes.
Add both lots of beans. The generously season with salt and pepper. Add the bay leaves, liquid smoke, cumin, soy sauce and mirin.
Add 8 cups of water and stir until thoroughly mixed.
Bring to a boil and reduce the heat to low-medium.
Cover and cook for 2 to 2 and a half hours, you want the black beans to be soft when you bite into them. If the soup is too thin, add a little cornflour mixed with water to thicken.
Spoon into bowls.
If serving with farofa, sprinkle it on top.