Heat oil in a dutch oven over medium-high heat. Add sausage, and crumble and brown until cooked through. Sprinkle flour over the sausage, and stir to coat.
Add diced potatoes, and pour in enough broth to just cover the potatoes. Bring to a simmer, and reduce heat to medium. Cover and simmer approximately 10 minutes or until potatoes are tender enough to break with a spoon.
Stir in drained tomatoes, half and half, and green onions. Bring soup back to a simmer, and cook for 2-3 minutes longer before serving.