Wash the potatoes, but leave the skins on, they are good for you, help the wedges stay together and they are oh-so delicious with a little charring from the grill!
Cut the potatoes into wedges, keeping each wedge the same size so that they cook evenly. There's a fine line here. You want the wedges to be thin enough to cook quickly, but the thinner the wedge, the more likely they will be to fall apart on the grill. I like to keep mine about a half inch thick.
Now for what some people say is the crucial step, soaking the potatoes in cold water. Cover them with cold water and let them soak for about 20 minutes. I say "some people" because everyone says to do it, but I haven't tried both ways to see if it matters. The soaking is supposed to remove sugar from the potatoes and increase their crispiness when cooked. Let's just be on the safe side here and trust all of the experts...
Light the grill and heat it to medium heat.
Thoroughly dry the potato wedges.
Toss the wedges in Olive oil and then sprinkle with a little cumin and generous amounts of Kosher salt and black pepper.
Using tongs, arrange the potatoes on the grill so that they aren't touching.
Grill the potatoes for about 5 minutes and then turn each wedge.
Continue to grill and turn the potatoes for about 5 minutes on each side. This is an estimate, keep an eye on the wedges and make sure none of them get TOO charred. Keep them moving around the grill, especially if you have hot spots on your grill. The total time should be around 20 minutes, but test a few to make sure they are cooked all of the way through.
Remove from the grill and serve!