Combine soy sauce, brown sugar, olive oil, and garlic in large ziploc bag.
Add cubed steak and shake to thoroughly combine.
Refrigerate for 1-2 hours or let sit at room temperature for 30 minutes.
If you refrigerate let sit at room temperature for 30 minutes before grilling.
Once ready to grill, thread cubed steak onto skewers.
To make the dijon vinaigrette, just combine dijon mustard, olive oil, lemon juice, garlic, and salt and pepper and stir to combine.
Toss with veggies.
Thread the veggies onto skewers.
Heat grill to medium-high heat.
If you like your veggies well done, add veggie skewers and cook 5-10 minutes, depending on how "done" you like your veggies.
Add steak skewers to grill and cook until meat is browned, turning every 2-3 minutes, about 10-12 minutes total.
Remove from grill and enjoy!