To Make Sauce: In a small bowl, whisk together sauce ingredients. Set aside.
To Cook Cauliflower Rice in Microwave: Place cauliflower rice in a microwave-safe bowl. Add water, 2 tablespoons soy sauce, 1 teaspoon sesame oil and add a little salt, pepper, and garlic powder. Mix well. Cover with plastic wrap and microwave for 3 minutes. Remove from microwave, carefully lift plastic wrap, and stir with a fork. Cover and microwave for an additional minute or so, until soft.
To Cook Beef: Heat oil in a large nonstick pan over medium high heat. Add beef, onions, garlic, and cook until browned, about 3-5 minutes, making sure to crumble the beef as it cooks. Pour beef into a colander in the sink to drain the excess fat. Add beef back to pan.
Add zucchini to a small bowl. Cook in microwave for 2 minutes until softened.
To the beef, add zucchini and stir in sauce. Mix well. Simmer until heated through, about 2 minutes.
To Serve: Add 1 cup cauliflower rice to each bowl. Top with 1 cup beef mixture with a little sauce. Mix to combine. garnished with sesame seeds, if desired.
Any leftovers freeze great. Mix together the beef mixture and cauliflower rice and pack in individual portion containers.