Set a large stockpot over medium heat and add the oil. Add the celery, carrots, and onion and sauté for 5 to 7 minutes.

Stir in the garlic and cook for about 30 seconds. Add the thyme and flour and cook for another minute or so.

Pour in the chicken broth and stir to dissolve the flour. Add the chicken. Turn the heat to high and bring to a boil, then lower the heat to medium-low to simmer.

Cover the pot almost fully, leaving the lid slightly off center so a little steam can escape. Simmer for 15 to 20 minutes, until the vegetables are tender and the chicken is cooked through (165°F). Bone-in thighs may take a little longer. While the soup simmers, bring a small pot of water to a boil for the couscous.

Add the couscous to the boiling water and cook, stirring a few times, for 8 to 10 minutes or until tender. Drain.

While the couscous cooks, move the chicken to a cutting board. Dice it or shred it with two forks, whichever you like best in a soup. If you used bone-in thighs, remove the bones (and the skin, if you’d like). Return the chicken to the pot along with the lemon juice, dill, and parsley. Stir it in, then taste and add salt and pepper as needed.

To serve, spoon some couscous into a shallow bowl and ladle the soup over and around it. Crumble feta on top and serve right away, with crusty bread and butter if you like.