Place the bone-in chicken thighs in a large stockpot. Pour in 3 to 4 quarts of cold water and bring to a boil. Cover, then reduce heat to low and simmer for 30–45 minutes, until the chicken is cooked through.

While the broth simmers, heat 1 tablespoon olive oil in a large pot or Dutch oven over medium. Add the diced onions and cook, stirring often, for 4–5 minutes until translucent.

Add carrots and celery to the onions. Cook, stirring frequently, for 10–15 minutes until softened. In the last 2 minutes, stir in the minced garlic, 2 teaspoons salt, 1 teaspoon pepper and the bay leaves.

When the chicken is done, remove the pot from heat. Use tongs to transfer the chicken to a cutting board and let it cool. Carefully strain the broth through a fine-mesh strainer into the pot with the vegetables.

When cool enough to handle, shred the meat with two forks (or your hands). Discard bones.

Add the lemon juice to the pot. Bring the soup to a boil, then reduce heat to low, cover, and simmer for 30 minutes or until the vegetables are tender.

In the last 5–10 minutes of simmering, return the shredded chicken to the pot to warm through.

Taste and adjust seasoning with additional salt and pepper if needed. Garnish with fresh chopped parsley and ladle into bowls.