Heat a large pot over medium high heat. Cook the sausage in the olive oil, breaking it up with the back of a wooden spoon until almost cooked thru, about 5 minutes. Add in the onion, salt and pepper, and cook until turning translucent, another 5 minutes, stirring occasionally. Add in the garlic and cook until fragrant, 30 seconds. Add in the sweet potatoes, chicken stock and bay leaf. Cook partially covered over medium heat until the sweet potatoes are tender, 20 minutes.

Remove the bay leaf, and add in the kale. Continue to cook over medium heat for 5 minutes until the kale is tender. Turn off heat, taste for salt and pepper, add more if necessary. Serve warm.