Heat a heavy cast-iron skillet over medium heat.
Add ground beef and cook, stirring occasionally, until browned and fully cooked (about 5 minutes).
Add chopped onion, minced garlic, and taco seasoning. Sauté for 1 minute until the onion softens.
Stir in chopped tomato and cook on low heat for 7–10 minutes until the mixture thickens slightly.
Add bell peppers and zucchini toward the end. Cook for 2 minutes, keeping the vegetables slightly crisp.
Serve the Healthy Ground Beef Vegetable Skillet hot, garnished with fresh cilantro and your favorite toppings.