Brown the beef: Heat oil in a large pot over medium-high heat. Add ground beef and break it up with a spatula. Cook until browned with crispy edges, about 6–8 minutes.
Drain excess fat if desired, but leave a little for flavor.
Sauté aromatics: Add onion and bell pepper to the pot. Cook 3–4 minutes until softened. Stir in garlic and cook 30 seconds until fragrant.
Build the base: Stir in tomato paste and cook 1 minute to caramelize.
Add diced tomatoes and beef broth, scraping the bottom to release browned bits.
Season well: Add chili powder, cumin, smoked paprika, oregano, cocoa powder, red pepper flakes (if using), salt, and black pepper. Stir to combine.
Add low-carb veg: Stir in diced zucchini. Bring the chili to a gentle simmer.
Simmer to thicken: Reduce heat to low and simmer uncovered 20–25 minutes, stirring occasionally, until it thickens and flavors meld.
If you want a thicker texture, sprinkle in xanthan gum and whisk, or melt in cream cheese.
Finish and balance: Stir in apple cider vinegar or lime juice. Taste and adjust salt, pepper, and heat.
Load it up: Ladle into bowls and add your favorite toppings: cheese, sour cream, avocado, jalapeños, cilantro, green onions, bacon, and a squeeze of lime.