Brown the sausage over medium heat in a Dutch oven or heavy soup pot. Break the meat apart into crumbles as it cooks. Remove to a plate.
Add the butter to the pan, along with the onions, garlic, Italian seasoning, red pepper flakes, and mustard powder. Saute, stirring pretty constantly, for a few minutes to soften the onion. Don't let the garlic brown.
Sprinkle in the flour and continue to cook and stir another minute.
Add the sausage back into the pan. Stir in the chicken broth or stock and lemon juice and bring everything up to a simmer, stirring almost constantly.
Add the tortellini and cook according to the package directions, generally just a few minutes. I like to add the cream, kale, and tomatoes a minute or two before they finish cooking. Bring back to a simmer and cook just until the pasta is tender and the kale has wilted.
Remove from the heat and stir in the Parmesan cheese. Add salt or fresh cracked black pepper to taste. Add a bit more lemon juice if needed.
Serve with extra Parmesan cheese.
Notes
If you want to make the soup ahead, keep the tortellini separate from the soup so it doesn't get mushy.The soup will keep up to 3 days in the refrigerator.Pasta soups in general do not freeze very well, so if you want to freeze this soup, plan to cook and add the tortellini after thawing.
Nutritional information is provided as a courtesy and is an estimate only. This information comes from online calculators. Although The View from Great Island attempts to provide accurate nutritional information, these figures are only estimates.
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