Chicken & Spinach Tortellini Soup

2 boneless, skinless chicken breasts, cubed
1 Tbsp canola oil
4 cups chicken broth
1 tomato, chopped
1 celery stalk, chopped
1-1/4 cups cheese-filled tortellini
1 garlic clove, minced
1/4 tsp dried oregano, crushed
1/8 tsp pepper
2 cups packed fresh spinach, chopped (or 1 cup frozen)

1. Cook chicken in oil until brown.
2. Add broth, tomato and celery, heat to a boil.
3. Stir in tortellini, garlic, oregano and pepper, heat to a boil.
4. Reduce heat to low and simmer, covered for 10 minutes.
5. Stir in spinach and simmer until tortellini is cooked, about 5 minutes.