Cook the veggies: Heat olive oil in a large pot over medium heat. Add onion, celery, and carrots with 1 tsp kosher salt. Sauté for 5-6 minutes until softened. Add garlic and cook for 1 more minute.
Add chicken and broth: Pour in chicken broth and soy sauce, then add the raw chicken thighs or legs. Stir in dried parsley and remaining 1 tsp kosher salt (or 2 tsp if skipping soy sauce).
Simmer: Bring to a boil, then reduce heat to low. Cover partially and simmer for 45-55 minutes, until the chicken is fully cooked and tender.
Shred the chicken: Remove chicken from the pot and let it rest for a few minutes. Shred it with two forks, discarding the bones. Return shredded chicken to the pot.
Cook the orzo: Stir in orzo and cook for 8-10 minutes, or until tender.
Finish the soup: Stir in butter, lemon juice, and lemon zest (if using). Taste and adjust seasoning with a splash of soy sauce or extra salt, if needed.
Notes
Chicken Substitutes: Boneless chicken thighs or breasts work too, but adjust cooking time to ensure tenderness.Soy Sauce: Adds umami and a richer golden color.Orzo Tip: If the soup thickens too much as the orzo absorbs liquid, add a splash of extra broth.Lemon Brightness: Add more lemon juice to taste if you prefer a stronger citrus flavor.