1. Heat 1 teaspoon oil in a large saucepan over medium-high heat. Add chicken and cook, stirring once or twice until no longer pink in the middle (2 minutes). Transfer chicken to a plate.
2. Add the remaining 2 teaspoons oil to the pan and heat over medium-low heat. Add carrot, garlic, coriander, salt, and pepper. Cook, stirring constantly, until fragrant (1 minute).
3. Stir in broth and lentils, increase heat to medium-high to bring to a boil. Reduce heat to maintain a simmer and cook, stirring occasionally, until the lentils are tender (20-30 minutes).
4. Add the cooked chicken, spinach, and juice and return to a simmer. Cook until heated through (1-2 minutes). Stir in dill to serve.