Preparation Melt butter in heavy medium saucepan over medium-high heat. Add leek and thyme. Sauté until leek begins to soften, about 3 minutes. Add broth, mustard greens and cabbage; bring to boil. Reduce heat to medium; simmer until all vegetables are tender, about 10 minutes. Season with hot pepper sauce, salt and pepper. Ladle soup into deep bowls. Top with croutons and cheese and serve.
Preparation Melt butter in heavy medium saucepan over medium-high heat. Add leek and thyme. Sauté until leek begins to soften, about 3 minutes. Add broth, mustard greens and cabbage; bring to boil. Reduce heat to medium; simmer until all vegetables are tender, about 10 minutes. Season with hot pepper sauce, salt and pepper. Ladle soup into deep bowls. Top with croutons and cheese and serve.