Chicken and Vegetable Dumpling Soup

Name: Chicken and Vegetable Dumpling Soup
Prep time: 30 min
Cook time: 30 min
Total time: 1 h
Cuisine: American
Ingredients: 1-2 teaspoons olive oil; 1 cup diced celery (about 2-3 stalks); 1 cup diced carrots; 1 cup diced yellow or white onion; 1 teaspoon salt (I use coarse, kosher salt); 1/2 teaspoon dried thyme; 1/4 teaspoon pepper; 8 cups chicken broth (I use low-sodium); 1 to 1 1/2 pounds boneless, skinless chicken breasts or 3-4 cups cooked chicken (see note); 1/2 cup water + 1/4 cup all-purpose flour to thicken; 1/2 cup frozen peas; 1 cup all-purpose flour (use 1 1/4 cups flour for sturdier dumplings); 2 teaspoons baking powder; 1/2 teaspoon salt; 1/4 teaspoon dried thyme or sage; 1/2 cup sour cream; 1/2 cup milk; 1 tablespoon vegetable or canola oil