In a large mixing bowl, whisk together tamari, oil, sugar, lime juice, onion powder, chili powder, black pepper, oregano, cumin, and salt. Add veggies and tempeh to the bowl and toss to coat. Transfer coated mixture to a large FoodSaver Vacuum bag, vacuum the air out and seal it. Refrigerate for at least one hour or overnight, to marinate. (If you don't have a FoodSaver place in zip lock bag and remove as much air as possible)
Preheat grill to 375F, and assemble skewers by alternating a mix of veggies and tempeh on either soaked bamboo skewers or metal ones, as shown above. Grill for 5 minutes on at least three sides, or until grill marks are prominent and veggies slightly tender. If there is leftover marinade in the bag, brush it over the skewers as they cook.
Serve skewers while hot, and if you have extra, remove the veggies from the skewers, tranfer them to another FoodSaver bag, and vacuum seal them, refrigerating or freezing them for later enjoyment!