Scrub the potatoes but don’t bother peeling. Cut the potatoes into 1/4″ thick slices, then turn the slices onto their sides and cut into 1/4″ strips. I find this easiest to do if I slice 1/4″ off the ends first and cut the ends into 1/4″ strips separately. Then you can stack the first 1/4″ slices and cut through them all at the same time to form the strips. If you're in a hurry, just cut into chunks. If you're using fingerling potatoes, just leave them whole! Note that the ones in the picture are not overdone! I used a mix of red, white and purple potatoes that I bought at the farmer's market.
Soak in a bowl of hot water for 10 minutes while you heat the oven to 450 F. (If you're in a hurry, you can skip this step but it does something about removing some of the starch.)
Drain the potatoes and pat dry with a towel or paper towels. Mix in a bowl with the oil and salt.
Spray a baking sheet with olive oil and spread the potatoes out in a single layer as much as possible. Bake 30 minutes or so, then turn over and bake another 5-10 minutes. Watch them the last few minutes as they can quickly go from perfect to overdone!
Note: I often jazz these up a bit with various seasonings that I add with the salt. It's a great way to use herb mixes you bought for some particular recipe or were given as a gift. I almost always add paprika to them as well.