1. Mix together the ground turkey, egg, onion, garlic salt, and pepper. Form meatballs using a tablespoon measure.
2. Heat the oil in a skillet over medium heat. Brown meatballs in oil. Transfer meatballs to a paper towel to drain.
3. In a soup pot, dissolve the bouillon cube in the boiling water. Stir in the undiluted mushroom soup. Add the carrots, celery, onion, and corn. Add the meatballs to the soup, and bring to a boil. Reduce heat, and simmer 25 to 30 minutes.