Cook the ground beef in a large pot over medium heat until completely browned, 7 to 10 minutes. Drain as much fat from the beef as possible. Add the onion and garlic to the beef; cook and stir until the onion is softened, about 5 minutes.

Add the tomato paste, crushed tomatoes, onion soup mix, beef bouillon cubes, bay leaf, mixed vegetables, and water to the ground beef mixture. Raise heat to medium-high, and bring the mixture to a boil. Stir the orzo pasta into the boiling liquid; cook until the orzo is tender, about 10 minutes. Season with salt and black pepper to serve.