Cook the diced bacon in a Dutch oven over medium heat for 5–6 minutes until crisp. Remove with a slotted spoon and set aside, leaving the fat in the pot.
Add the ground beef to the hot fat and cook for 6–8 minutes, breaking it apart, until deeply browned.
Add the onion and cook 4 minutes until softened. Add the garlic and cook 30 seconds more.
Stir in the chili powder, smoked paprika, and chipotle powder. Cook for exactly 60 seconds, stirring constantly, until fragrant.
Stir in the tomato paste and cocoa powder. Cook 2 minutes until darkened and toasted-smelling.
Add the diced tomatoes and beef broth, scraping the bottom of the pot. Bring to a low simmer, cover partway, and cook 60 minutes, stirring occasionally.
Stir in the masa harina and drained kidney beans. Simmer uncovered for 20 minutes, until the chili coats the back of a spoon.
Remove from heat and stir in the apple cider vinegar and lime juice. Taste and adjust salt.
Let the pot rest off heat for 10 minutes. Stir the reserved bacon back in, then serve with desired toppings.