Rub the salt, pepper, and onion powder onto the roast, and place it into the slow cooker. Add the mushrooms.
Whisk two cups of the chicken broth with the Dijon, balsamic vinegar, syrup, thyme, and half of the garlic. Pour mixture over roast.
Cook on low for 8 to 10 hours or on high for 4 to 6 hours.
About 10 to 20 minutes before serving the meal, cook the frozen cauliflower according to package directions; drain excess liquid. In a medium bowl, mash the cooked cauliflower with the remaining chicken broth and garlic.
Serve beef stew on top of mashed cauliflower to enjoy as a complete Lean & Green Meal.
Lean & Green Meal: 300 calories | 10g fat | 11g carbohydrates | 42g protein