In a large pot, heat oil over medium heat. Cook onions 3–4 minutes until translucent, then add garlic and ginger, sauté 1 minute until fragrant.

Add cumin seeds, turmeric, coriander, and red chili powder, stirring constantly for about 30 seconds until the mixture turns aromatic and the colors deepen richly.

Nestle the chicken thighs into the spices, cooking 4–5 minutes per side until golden-brown edges appear and juices start running clear.

Stir in brown lentils and diced tomatoes, ensuring each piece is coated. Pour in chicken broth, scraping any browned bits off the pot bottom.

Bring to a gentle boil, then reduce heat to low. Cover and simmer 25–30 minutes until lentils are tender and chicken is cooked through.

Uncover, sprinkle garam masala, squeeze lemon juice evenly, then simmer 1–2 minutes. Garnish with cilantro before serving warm.