Greek Lemon Chicken Soup (Avgolemono Soup)

Name: Greek Lemon Chicken Soup (Avgolemono Soup)
Prep time: 15 min
Cook time: 25 min
Total time: 40 min
Cuisine: Mediterranean
Ingredients: 1 cup shredded chicken; 2 tablespoons butter; ½ small onion (chopped); 1 stalk celery (chopped); ⅓ cup matchstick carrots; ¼ cup uncooked orzo; 1 teaspoon minced garlic; ½ teaspoon oregano; 1 egg yolk; 2 cup chicken broth; 1 squeeze of lemon juice; salt and pepper (to taste)