Place your large pot on the stove and add the olive oil over medium heat. Once shimmering, add the diced onion, chopped carrots, and celery. Sauté for about 8 minutes, stirring occasionally, until the vegetables soften, release their aroma, and become slightly translucent.
Push the vegetables to the sides of the pot and place the chicken thighs in the center. Let them brown undisturbed for about 5 minutes per side, until golden and slightly crisp, then flip to brown the other side. The meat should develop a deep, rich aroma.
Pour in the chicken stock, ensuring it covers all the ingredients. Add the sprigs of thyme and the bay leaf. Bring the mixture to a gentle simmer, just below boiling, and let it cook uncovered for about 45 minutes. During this time, the broth will deepen in flavor and the chicken will become tender.
Remove the chicken thighs from the pot and place them on a cutting board. Once cool enough to handle, shred the meat into bite-sized pieces using two forks. Discard the bones and herbs.
Return the shredded chicken to the pot and stir to combine. Season with salt and pepper to taste, then let the soup simmer for another 10 minutes so the flavors meld and the chicken reheats thoroughly.
Taste the broth and adjust the seasoning if needed. The vegetables should be tender, the chicken moist, and the broth clear and fragrant. Serve hot in bowls, enjoying the comforting aroma and nourishing warmth.
