Heat 2 tablespoons oil in a large pot or Dutch oven over medium heat. Add curry powder and cook 1-2 minutes, stirring constantly, until fragrant and slightly darkened. Add diced onion, carrot, garlic, and ginger; sauté 5 minutes until onion softens and turns translucent.
2 tbsp curry powder, 2 tbsp olive oil, 1 large onion, 2 medium carrots, 3 cloves garlic, 1 tbsp fresh ginger
Pour in 6 cups chicken broth and add chicken thighs, lentils (if using), salt, and black pepper. Bring to a boil, then reduce heat to low and maintain a gentle simmer for 30 minutes. Check chicken reaches 165°F with an instant-read thermometer.
6 cups chicken broth, 1.5 lbs chicken thighs, 0.5 cup red lentils, 1 tsp salt, 0.5 tsp black pepper
Remove pot from heat. Transfer chicken thighs to a cutting board and shred with two forks into bite-size pieces. Return shredded chicken to the pot and stir to distribute evenly.
1.5 lbs chicken thighs
Stir in diced apple and coconut milk. Return pot to low heat and simmer gently for 10-15 minutes until apple softens but maintains slight texture. Do not boil to prevent coconut milk from breaking.
1 medium apple, 13.5 oz coconut milk
Taste and adjust salt, curry powder, or black pepper as needed. Ladle into bowls and garnish with fresh cilantro if desired. Let soup rest 5 minutes before serving to let flavors settle.
1 tsp salt, 2 tbsp curry powder, 0.5 tsp black pepper, fresh cilantro