Fill your Vortex BBQ with charcoal and light it up while preparing the potatoes.
Slice potatoes in half lengthwise, then half again lengthwise, and finally one more time lengthwise (i.e. you're cutting them into 1/8ths). You don't want them super thin, so for smaller potatoes you might only have to cut them 1/4ths. Transfer to a bowl.
Drizzle the potatoes with the oil and toss to coat.
Sprinkle the potatoes with the seasoning and baking powder and toss to coat. I've found that stirring them with your hands works best.
Once the charcoal is just ashed over place the potato wedges in a circle around the edges of your grill. Don't let the potatoes touch. It's ok if you need to put them in two or three rows. If some pieces are thicker than others try to locate those nearer the fire.
Place the cover on the grill with the top and bottom vents wide open.
Cook for 20-30 minutes, rotating the lid 90 degrees every 5 or so minutes. Start checking the potatoes after 15 minutes. Sometimes one side off the grill needs more heat as the wedges there aren't cooking quite as quickly as others. Just rotate the lid so the vent is near that side and let cook a bit longer.