In a large pot, sauté onions in oil until beginning to brown.

Add sweet potatoes and mushrooms and sauté an additional 10 minutes. Add flanken and brown on both sides.

Pour in water to generously cover vegetables and add spices; mix to combine.

Bring soup to a boil and lower heat. Simmer for two hours.

Remove flanken from pot and cut into small pieces. Return to soup and serve.