In a large mixing bowl, combine the ground beef, onion, rice, egg, Worcestershire sauce, garlic powder, onion powder, salt and pepper.
1 pound lean ground beef, ½ medium yellow onion, ½ cup long-grain rice, 1 large egg, 1 tablespoon Worcestershire sauce, 1 teaspoon garlic powder, 1 teaspoon onion powder, ¾ teaspoon fine sea salt, ½ teaspoon freshly ground black pepper