In a large pot over medium heat add oil, onion and garlic. Saute for 10 minutes or until onions are beginning to caramelize a little.
Add sweet potatoes, tomatoes, carrots, bay leaf, rosemary, oregano, thyme, paprika and vegetable broth/water. Turn heat to high, bring to a boil, cover and reduce heat to a simmer (med-low). Simmer for 30 minutes.
Add tapioca starch/water mixture and mustard. Mix well and simmer 5 minutes longer or until thickened slightly (it will continue thicken when the heat is turned off).