Preheat the oven to 425°F.
Assemble the skewers as directed and place them on a parchment-lined baking sheet or a wire rack set over a baking sheet.
Drizzle with olive oil and season with salt, pepper, extra sumac, and garlic powder.
Bake for 20-25 minutes, turning once halfway through, until the meatballs are cooked through and the vegetables are tender.
For a little extra color and char, broil for 2-3 minutes at the end of cooking, keeping a close eye on them.
The meatballs should reach an internal temperature of 160°F for lamb or beef.