In a large mixing bowl, add your frozen brussels sprouts. No need to thaw or chop. Drizzle on the oil and balsamic vinegar and stir to coat. Sprinkle on the garlic powder, onion powder, and salt and stir well.
12 ounces frozen brussels sprouts, 2 teaspoons oil, 1 teaspoon garlic powder, ½ teaspoon onion powder, ½ teaspoon salt, 2 teaspoons balsamic vinegar