Prep the chicken: Pat the chicken dry and season all over with 1 teaspoon salt, 1/2 teaspoon black pepper, cumin, paprika, and a pinch of red pepper flakes if using. Set aside while you chop vegetables.
Heat the pot: In a large heavy pot or Dutch oven, warm the olive oil over medium-high heat. Add the chicken and sear 3–4 minutes per side until browned.
You’re building flavor here, not fully cooking. Transfer chicken to a plate.
Sauté the aromatics: Lower heat to medium. Add onion, carrot, and celery with a pinch of salt.
Cook 4–5 minutes until softened. Stir in garlic, turmeric, and dried thyme for 30 seconds until fragrant.
Build the base: Pour in the diced tomatoes with their juices. Scrape up any browned bits from the bottom of the pot.
Add the rinsed lentils, bay leaf, and chicken broth. Stir well and bring to a gentle simmer.
Simmer with chicken: Nestle the seared chicken (and any juices) back into the pot. Cover and simmer on low for 20–25 minutes, stirring occasionally, until lentils are tender but not mushy and chicken is cooked through.