Remove casings from sausage and discard; crumble the meat. In a stockpot, cook the sausage, stirring, over moderately low heat for 4 minutes. Add the pepperoni and cook 2 minutes more or until the fat is rendered. Drain the sausage and pepperoni on paper toweling. Pour all but 1 teaspoon of the fat from the stockpot and discard.
Add the onion and celery to the stockpot and cook, covered, stirring occasionally, over low heat for 8 minutes or until softened. Return the sausage to the stockpot and add the stock, kale and garlic. Bring to a simmer, cover, and cook for 10 minutes.
Stir in the potatoes, red pepper sauce and salt, and simmer, covered, 20 minutes more or until the potatoes and kale are tender. Add the beans and cook just until heated through. Makes 6 1½-cup servings.