Heat 2 Tbsp olive oil in a large soup pot over medium-high heat.
Season 1 1/2 lbs chicken thigh strips with 1 tsp kosher salt and 1/2 tsp black pepper, then brown in pot for 5-7 minutes.
Remove chicken to a plate.
Reduce heat to medium and add 1 cup diced onion, 1 1/2 cups diced carrots, and 1 1/2 cups diced celery with a pinch of salt.
Cook vegetables until softened, 4-5 minutes.
Add 4 minced garlic cloves and 3/4 tsp dried oregano, cooking for 30 seconds.
Add 8 cups chicken stock and 3 bay leaves, then bring to a simmer.
Stir in 1 cup dried pasta and the browned chicken.
Simmer partially covered until pasta and vegetables are tender, 10-12 minutes, stirring occasionally.
Remove and discard bay leaves.
Stir in 1 1/2 Tbsp lemon zest, 3 Tbsp lemon juice, and 3 Tbsp chopped parsley.
Taste and adjust salt, pepper, and lemon juice as needed.