Cozy Lemon Chicken Orzo Soup

1 yellow onion

2 carrot

3 celery

2 tbsp unsalted butter

4 garlic

1 tbsp italian seasoning

6 cup chicken broth

1 tbsp olive oil

1 tbsp all purpose flour

1 skinless boneless chicken breast

1 cup orzo pasta

1 lemon

1 salt

1 black peppercorn