Preheat the oven to 350° F. Spray a 9×13-inch baking pan with non-stick spray.
Combine soy sauce, ½ cup water, brown sugar, ginger and garlic in a small saucepan and cover. Bring to a boil over medium heat. Remove the lid and cook for one minute once boiling.
Stir together the cornstarch and 2 tablespoons of water in a separate dish until smooth. Once the sauce is boiling, add the cornstarch mixture to the saucepan. Stir to combine. Cook until the sauce starts to thicken then remove from heat.
Place all the veggies evenly in the prepared baking dish. Pour 3/4 cup of the sauce evenly over the veggies. Cover the pan with foil and bake for 35 minutes or until the veggies are tender.
Meanwhile, cook the ground beef in a large skillet over medium-high heat. Season with salt and pepper. Cook and crumble until the beef is no longer pink. Drain any grease. Set aside.
Remove the baking dish from the oven. Carefully remove the foil. Pour the cooked ground beef and the cooked rice evenly over the veggies.
Pour most of the remaining sauce all over the top (reserving a bit to drizzle over the top when serving). Gently toss everything together until combined.
Return to the oven and cook uncovered for 10 minutes or until everything is heated through. Remove from the oven and let it stand 5 minutes before serving. Drizzle each serving with remaining sauce. Enjoy!