Preheat the pan: Set a large skillet over medium heat. If your beef is very lean, add the olive oil to prevent sticking.
Brown the beef: Add the ground beef and break it up with a spatula.
Cook until no pink remains, about 5–7 minutes. Drain excess fat if needed.
Build the base: Add the onion and bell pepper. Cook 3–4 minutes until softened.
Stir in the garlic and cook 30 seconds until fragrant.
Season well: Sprinkle in chili powder, cumin, smoked paprika, oregano, salt, black pepper, and red pepper flakes if using. Toast the spices for 30–60 seconds, stirring often.
Add veggies and sauce: Stir in the zucchini, corn, black beans, diced tomatoes (with juices), tomato paste, and broth. Mix until the tomato paste dissolves.
Simmer: Bring to a gentle simmer.
Reduce heat to medium-low and cook 8–10 minutes, stirring occasionally, until the zucchini is tender and the sauce thickens.
Brighten it up: Turn off the heat. Add lime zest and juice. Taste and adjust salt, pepper, or chili powder as needed.
Finish and serve: Sprinkle with chopped cilantro.
Serve over rice or cauliflower rice, tuck into tortillas, or spoon over a salad. Add toppings you love.