Put oil in a large saucepan over medium-high heat. Add the onion, garlic, ginger, and chile, and saute for 3 minutes, or until the onions are softened. Add the coriander seeds, garam masala, paprika, turmeric, and salt and toast for 10 seconds and then add the tomato paste. Stir well and then add the chicken thighs, turning them frequently as they cook. Add the tomatoes, potatoes, cilantro, and water and mix well. Bring the mixture to a boil and then reduce the heat to a simmer. Cover with a lid and let cook for about 20 to 25 minutes, or until the chicken is cooked through. Serve the chicken masala with rice.