1In large Dutch oven, stir together chicken, broth, water, onion, sage, thyme, 1 teaspoon of the salt and 1/2 teaspoon of the pepper. Heat to boiling over medium-high heat. Reduce heat to medium-low; simmer 20 minutes, stirring occasionally, until chicken is no longer pink in center. Add frozen vegetables. Heat to boiling over medium-high heat.
2In medium bowl, stir Bisquick mix, buttermilk, poultry seasoning and remaining 1/4 teaspoon each salt and pepper until blended. Drop dough by rounded teaspoonfuls into boiling mixture in Dutch oven. (Don't let dumplings touch.) Reduce heat to medium-low; cook uncovered 10 minutes, stirring occasionally to prevent dumplings from sticking. Cover; cook 10 minutes longer. Garnish with thyme sprigs, if desired.