Heat the oil in a large stock pot over medium-low heat. Add the onions and stir. Cover and sauté, stirring occasionally, until the onions begin to brown, about 20 minutes. Remove the lid and continue to sauté, until onions caramelize and turn a deep golden color, about 20 more minutes.

While the onions are caramelizing, place the garlic, chili peppers, and cilantro into the bowl of a food processor and pulse, scraping down the sides of the processor once or twice, to form a fine paste.

Once the onions have caramelized, add the chili pepper mixture to the pot and stir to combine. Cover and cook on medium-low heat for 5-10 minutes, stirring occasionally.

Add the grated tomato and stir to combine. Cover and cook for 5 minutes longer.

Add the curry powder and salt and stir for 1-2 minutes until the dry and wet mixtures (masalas) incorporate evenly.

Add the chicken and potatoes to the pot. Cover with water up to an inch above the chicken and potatoes and bring to a boil. Reduce the heat to medium-low, mix and cover. Simmer for 1 hour to 1 hour and 20 minutes covered, until the chicken is falling off the bone. Do not mix while cooking. You can shake the pot gently and carefully while holding the handle 2-4 times during the cooking process to make sure the chicken and potatoes aren’t getting stuck to the bottom and burning. Adjust heat to a lower setting if necessary.

Serve hot over basmati rice.