Brown the Beef and Sauté Aromatics
Heat the olive oil in a large pot or Dutch oven over medium-high heat. Add the ground beef, salt, and pepper. Cook, breaking up the meat with a spoon, until it is browned all over. Drain any excess fat from the pot. Add the chopped onion and cook for 5-7 minutes, until softened and translucent. Stir in the minced garlic and cook for one more minute until fragrant.

Bloom the Spices
Reduce the heat to medium. Stir in the tomato paste, chili powder, cumin, cocoa powder, oregano, paprika, and cayenne pepper. Cook for one minute, stirring constantly, until the spices are toasted and deeply aromatic. This step is crucial for developing a rich, deep flavor.

Combine and Simmer
Pour in the fire-roasted tomatoes and beef broth, using a spoon to scrape up any browned bits from the bottom of the pot. Stir in the rinsed and drained kidney beans. Increase the heat to bring the mixture to a boil, then reduce the heat to low, cover the pot, and let it simmer for at least one hour, stirring occasionally to prevent sticking.

The Finishing Touch
After simmering, turn off the heat. Stir in the apple cider vinegar to brighten and balance all the flavors in the chili. Taste and adjust the seasoning, adding more salt if needed, before serving.