Put the potatoes, unpeeled, into a large pot and cover with cold water. Bring to a boil and simmer until almost tender, about 15-20 minutes. Do not overcook, or they will fall apart and you won't be able to cut them into fries.
Drain and dry the potatoes and allow to cool enough to handle.
Carefully cut each potato lengthwise into about 6 wedges. (Original recipe said 4 wedges, but those are too thick in my opinion.) You do have to be careful, since they are already cooked, that they could crumble or fall apart.
Place the wedges on a baking sheet and brush both sides of the potatoes with oil.
In a small bowl combine chili powder, salt and cumin. Sprinkle over the potatoes.
Grill the potato wedges for 3 to 4 minutes per side, until golden brown