In a small bowl, whisk together all of the steak marinade ingredients. Place steak cubes into a large resealable plastic bag and add marinade. Turn bag a few times to make sure each piece of steak is coated. Marinate in the refrigerator for at least 30 minutes, up to 2 hours.
Preheat grill to medium high heat.
In a small bowl, whisk together the melted butter, olive oil, and garlic. Place the cubed bread into a large bowl. Pour melted butter mixture over the bread, toss to combine.
Remove meat from refrigerator, discard marinade. Thread meat, garlic bread, and cherry tomatoes onto skewers as desired. Grill each kabob for 3-4 minutes per side.