Steps
1. Pat the beef dry and season it lightly with salt and pepper.
2. Warm the oil in a small saucepan over medium heat. Add the beef and brown on several sides, about 4 minutes, then transfer it to a plate.
3. Add the onion to the pan and cook until softened, about 3 minutes. Stir in the garlic, tomato paste, cumin, paprika, and chili powder; cook for 30 seconds.
4. Pour in the broth, scraping up browned bits. Return the beef and any juices to the pan. Cover and simmer gently until the beef is fork-tender, about 45–60 minutes, adding a splash of broth if the sauce gets too thick.
5. Stir in the chopped chocolate until melted and the sauce looks glossy. Add the lime juice and adjust the salt and pepper.
6. Spoon the beef and sauce over the cooked rice and serve hot.