Heat the olive oil in a large skillet over medium heat.
Add the chopped onion and minced garlic to the skillet, and sauté for about 2-3 minutes, until the onions are translucent.
Increase the heat to medium-high and add the ground beef to the skillet. Cook for about 5-7 minutes, breaking it apart with a wooden spoon until it is browned and cooked through.
Stir in the diced bell pepper and zucchini, cooking for an additional 3-4 minutes until the vegetables are softened.
Add the black beans, corn, cumin, chili powder, salt, and pepper. Stir well to combine all ingredients.
Reduce the heat to medium, and let the mixture simmer for about 5 minutes to heat through and allow the flavors to meld.
Taste and adjust seasoning if needed.
Serve hot, garnished with fresh cilantro if desired.