You can use as many potatoes as desired, if they are small I generally have at least 3 per person. Preheat your oven to 450 degrees. Wash potatoes, pierce and place in a long oblong dish (I like glass the best but you can use aluminum).
Coat potatoes with a good quality olive oil and turn potatoes to distribute, make sure there is some excess in the bottom of the pan also. Spread kosher salt over all and roast potatoes, turning occasionally for 1 - 1 1/2 hours.