In 4-quart Dutch oven cook mushrooms and onions in hot oil over medium heat 6 to 8 minutes until liquid has evaporated. Stir in flour until combined. Add broth all at once; cook and stir until thickened and bubbly. Stir in chicken, peas, olives, lemon juice, and sage. Return to boiling.
Prepare Buttermilk Dumpling dough; drop dough, 1/3 cup at a time, onto boiling soup. Simmer, covered, 10 minutes or until toothpick inserted near centers comes out clean. To serve sprinkle with green onion and Fried Sage Leaves.
Fried Sage Leaves
Heat olive oil over medium heat. Add sage sprigs, 2 at a time. Cook until crisp for 30 to 60 seconds; drain.
In a medium bowl combine flour, baking powder, baking soda, and salt. Stir in green onions and parsley. Add buttermilk and olive oil; stir until moistened.