Char the bell and chile peppers under a hot broiler until the skins are evenly blackened. Place in a bowl and cover to cool to handle. Wipe the charred skins away with paper towels and seed the peppers. Reserve for later use.
Heat a large skillet over medium-high heat, add the oil. Sprinkle the chicken thighs with salt and pepper on both sides. Add the chicken to the hot oil and brown on both sides, 4 to 5 minutes. Remove the chicken to a plate and reduce the heat a bit. Add the garlic, bay leaf, cinnamon, ginger, onions, paprika, cumin and some salt and pepper, and cook to soften a bit, stirring occasionally. Add a splash of vinegar.
Place the peeled peppers in the bowl of a food processor with 1 cup of the stock, and process until pureed. Add the puree to the pan, thin with about 1/2 cup water and slide the chicken back into the pan. Reduce the heat to a simmer and finish cooking the chicken through. Turn off heat and cover until you serve.
To serve, heat the remaining 1 1/2 cups stock (or 1 cup stock and 1/2 cup water) and the butter to a boil with the rice. Bring to a bubble, then reduce the heat to low and cover. Simmer the rice for about 15 minutes. Turn off the heat and let stand 5 to 10 minutes, then fluff with fork.
In shallow bowls, top the rice with the chicken in spicy sauce, garnish with scallions before serving.
Get Rachael's shopping list for this episode's recipes here.