If you want to grill the potatoes:
Peel them and cut them into 1" chunks. Slice a medium sized onion and chop some peppers. Make a "bowl" out of heavy duty foil and place all of the above into the bowl. Top with a bit of olive oil, butter, seasonings (I like garlic, an herb like marjoram or oregano), top with some grated cheese and close the top of the bowl. This might leak so I like to drop this into a foil pan and punch some holes in the foil to let the smokey smell into it. Then just drop it on your grill for about 30 minutes or so.
If you are using really firm potatoes, you can speed up the process by microwaving them for a few minutes before you drop them in the foil.
Microwave recipe for Lyonnaise:
Peel and slice about 4 medium potatoes
Slice 1 medium onion
2 tblsp butter
1/4 tsp marjoram
healthy dash garlic
1/4 cup chicken boullion
Salt and pepper to taste
Place 2 tblsp butter in a 2 quart microwave dish. Nuke until butter is melted. Add onions, cover and nuke for 2 minutes. Add the remaining ingredients and stir. Cover and nuke for 3 minutes, stir, replace lid and nuke for another 3 minutes. If you are using more potatoes than the recipe, you might need to nuke for another 3 minutes. Potatoes will be fork tender. Let it stand 5 minutes before serving.
And if you make this one, sing along: These potatoes are not fried, their lyonnaised.....(from the Eagle's song, you can't hide your lying eyes)