Dry off the meat with a paper towel and generously sprinkle with salt and pepper. Heat a large skillet on medium high heat. Add 1 tablespoon of olive oil. Brown the meat in batches, ensuring the pieces don't touch. If you overcrowd the pan, the meat with steam and not sear. Sear the meat for 1-2 minutes until deeply browned and then flip over and sear the other side. Remove the beef to a large slow cooker each batch at a time, until all meat has been seared.
Reduce the heat to low medium and add 1 more tablespoon of oil. Add the celery and onion and saute for about 5 minutes, until they soften. They should be brown, picking up all of the beef flavor!
Add the 6 cloves of minced garlic and chopped jalapeno. Add the chili powder, cayenne, cumin, oregano, garlic powder, and brown sugar. Stir all together and let the spices toast into the vegetables for 1 minute.
Add the beef broth and scrape the bottom of the pan. Slowly pour in the masa harina, stirring constantly, breaking up any clumps. Pour the mixture into the slow cooker.
Add the tomato paste, crushed tomatoes, kidney beans, and bay leaves to the slow cooker and stir all together.
Put the lid on the slow cooker and cook on high for 6 hours or low for 8-10 hours. Once it's done cooking, break up the chunks of meat with a fork or wooden spoon. Serve with fresh jalapeno, cheddar cheese, avocado, and cilantro.