In a large bowl, combine the thyme, sage, salt, and pepper. Add the beef and toss to coat well.
Heat the oil in a large saucepot or Dutch oven over high heat. Add half of the beef and cook, stirring, for 4 minutes, or until browned. Place the browned beef in a bowl. Repeat with the remaining beef.
Return all the browned beef to the pot. Add the garlic and ginger and cook, stirring, for 1 minute. Stir in the broth and water and bring to a boil. Reduce the heat to low, cover, and simmer, stirring occasionally, for 1 1/2 hours, or until the beef is tender.
Add the tomatoes, sweet potatoes, mushrooms, onions, and carrots. Bring to a boil over high heat. Reduce the heat to low, cover, and simmer, stirring occasionally, for 40 minutes, or until the vegetables are tender. Add the spinach, mustard greens, or kale, cover, and cook for 2 minutes, or until wilted.