Heat half the oil (2 tablespoons) in a large pot over high heat. Season the meat well with salt and the Shisanyama spice mix. Brown on all sides in batches, making sure not to overcrowd the pot, then set aside. Reduce the heat to medium and add the remaining oil. Add the onion, carrots and celery, and sauté for about 10 minutes, or until the vegetables start to colour and caramelise. Add the garlic and thyme, and cook for 1 minute, stirring often. Pour in the chopped tomatoes and cook for a further 5 minutes. Add the vegetable stock and bay leaves. Bring to a simmer, then stir in the soaked speckled beans. Cover and cook for 20 minutes. Return the browned meat to the pot, lower the heat, and simmer gently for 40 minutes, stirring and checking every 15-20 minutes. Once the meat is tender and the beans are nearly cooked, mix in the potatoes and barley. Continue to cook for another 20-25 minutes, or until the barley is soft and the soup is thick and rich. Taste and adjust the seasoning with salt and pepper.
Scatter with chopped parsley and serve with fresh bread, if using.