Dice onion, mince garlic; dice bell pepper and carrots. Grate zucchini.
In a large skillet, heat the oil over medium low heat. Add onion and garlic. Saute for 5 minutes or until softened.
Add bell pepper, carrot and zucchini, stir to combine.
Raise heat to medium and saute about 10 minutes or until most of the moisture has evaporated.
Add ground beef, and cook until completely browned, 5-7 minutes.
Stir in corn. Add diced tomatoes with juice, tomato paste, vinegar, brown sugar, mustard, chili powder, and salt and stir to combine.
Continue to cook for about 10 minutes.
Serve on buns with blackberries on the side.