- Heat olive oil in a large heavy-bottomed pot over medium heat. Add onion and sauté until translucent and soft, 5–7 minutes. Stir in garlic and cook 1 minute until fragrant. Add celery and sauté 3–5 minutes to soften and build flavor. 
- Add carrots, then pour in broth. Add bay leaf and thyme. Bring to a gentle boil, reduce to low, cover, and simmer 25–30 minutes until carrots are tender. Skim any foam for a clear broth. 
- Stir in cooked grains and simmer 5–10 minutes to heat through and absorb flavor. Season with salt and pepper to taste, layering seasoning as needed. Remove bay leaf and serve; garnish with chopped parsley if desired.