1. In a slow cooker, add ground beef, breaking it apart with a wooden spoon. Next, layer in the following ingredients: onion, lentils, zucchini, corn, tomatoes, thyme and salt. Pour in beef broth, stirring gently.
2. Set slow cooker to high heat for 5 hours. Stir periodically. Turn off heat, remove stems of thyme and serve.
1. Leftover soup freezes well! Let the soup cool, then scoop into a freezer-safe container. Use within 1 month.
2. If needed, add more beef broth to thin out leftovers.
3. Add grated garlic for another flavor.