Create cubes that are same size and thickness so they cook evenly and at the same rate.
Cut 1 inch strips across grain, then cut each strip into 1 inch cubes.
Prepare and Cook Skewers
Soak bamboo skewers for a minimum of 1 hour.
Place beef cubes into a zip top bag and add oil. Toss to coat. Add about ½ of the rub and toss. Continue to add rub, a bit at a time, until the meat is fully coated (you may have leftover rub). Allow the meat to rest at room temperature for 30 min.
Preheat the grill for direct high heat (450˚F to 550˚F).
Meanwhile, cut bell peppers into 1 inch pieces.
Thread the meat, bell pepper pieces, and 4 tomatoes, alternating meat and vegetables.*
Grill the skewers on direct high heat with the lid closed as much as possible, turning every 2 minutes or so. Cook until the skewers reach your desired doneness (about 6-8 minutes for medium rare, internal temperature of 130˚F-135˚F)** Serve warm.
Notes
*Lay the pieces out and try to make the kebabs even.
**If you prefer larger 1 ½ inch cubes, grill for 8-10 minutes.
Note: If some cubes are a little smaller than the rest, combine them onto one skewer and grill for less time.