Prepare all ingredients (mise en place): wash, peel, and chop vegetables; cut chicken into 1-inch pieces.
Heat 1 tbsp olive oil in a large heavy pot over medium heat. Add onion and sauté 5–7 minutes until translucent and lightly golden.
Add minced garlic and cook 60 seconds, stirring, until fragrant (do not brown).
Push aromatics to one side and sear chicken pieces in a single layer 3–4 minutes per side until lightly browned (work in batches if needed). Stir to combine.
Add diced carrots and sliced celery; cook 5–7 minutes, stirring occasionally, to soften slightly.
Stir in dried thyme, crushed rosemary, and the bay leaf; cook 1 minute to toast the herbs.
Deglaze with broth and add diced tomatoes with juices. Scrape up browned bits. Bring to a gentle boil, then reduce to a low simmer, cover, and cook 25–30 minutes. Add optional autumn vegetables now so they become tender.
Stir in cooked barley or wild rice blend and simmer 5–10 minutes more to heat through and thicken slightly.
Season to taste with salt and freshly ground black pepper. Remove and discard the bay leaf.
Ladle into bowls and garnish with chopped parsley or chives, if desired. Serve hot.
