1. Heat oven to 350 degrees. In a Dutch oven or other large, heavy-bottomed ovenproof pan, heat the oil over medium heat until hot but not smoking. Add the onions and cook, stirring occasionally, until translucent, 5 to 7 minutes. Add the garlic, ginger and chili, and cook, stirring often, until slightly softened, about 1 minute. Add cinnamon, cardamom and coriander, and cook, stirring constantly, for about 30 seconds.

2. Add thighs to the pot along with the pepper, potatoes, coconut milk and just enough chicken stock to half-cover the thighs and potatoes. Turn heat to high, bring just to a simmer, then cover and put in the oven. Cook until potatoes are tender and chicken thighs are cooked through, 45 minutes to one hour.

3. Use a slotted spoon to transfer the chicken and potatoes to a serving dish. Tent loosely with foil and let rest. Skim as much fat as possible from the surface of the sauce, then return to a simmer over medium-high heat and simmer until slightly thickened, 5 to 6 minutes. Remove from heat, stir in the lime juice and cilantro, and adjust seasoning as necessary. Pour the sauce over the thighs and potatoes, and serve.