In a food processor, combine the thyme, onion, scallions, garlic, and scotch bonnet pepper, if using. Process until smooth. Add some vegetable oil during the process, if needed. Rub the chicken with the marinade and let sit for about an hour. The more the better.
Heat a large pan or pot and add the curry and cumin. Toast for a minute, then add the vegetable oil. Now add the chicken with all the marinade and toss to cover in the curry and cumin. Add the diced potatoes. Season with salt and pepper. Add the chicken stock or water.
Cover and bring to a boil. Reduce the heat and simmer for 25 minutes. Uncover and add more stock or water if the chicken is sticking to the bottom of the pan. Now cook uncovered for 20 minutes more until the liquid has somewhat thickened. Enjoy!