For the spice mix: In a small bowl, mix to combine the ground cumin seeds, garlic powder, paprika, chile flakes, and ground coriander seeds.
For the chili: Heat 1 tablespoon of the vegetable oil in a cast-iron pan over medium-high heat. Add the ground beef to the pan and cook, stirring frequently, until the moisture has evaporated, and the beef is browned. Drain the beef of any fat that has rendered, and deglaze the pan with half of the beer.
In a separate pot, add the remaining tablespoon vegetable oil, and add the onion, garlic, peppers, and okra, and saute over medium-high heat. Sprinkle over the chili spice mix, and the chipotle pepper, stirring to combine. Deglaze the pot with the remaining beer, and add the browned beef.
Add the diced tomatoes, and stock, and then bring everything to a boil. Place the lid over the pot, and reduce the heat to a simmer. After 1 hour, add in the kidney beans, and cilantro stems. Keep cooking for another 30 minutes over low heat.
Adjust the chili's seasonings with salt, and black pepper, to taste. Switch off the heat and garnish with the cilantro leaves.