Remove the tough stems from the kale by pulling the leaves away from the stem. Save the stems for smoothies or juicing.
Submerge the leaves into a bowl of cool water, swoosh them around, and let sit for a few minutes. Lift the kale out of the water to drain, leaving the dirt and grit behind. Don't pour the kale and water out at the same time, or it will still be dirty.
Dry the kale thoroughly by running it through a salad spinner or wrapping in a towel and swinging it around outside. Place the leaves on a large baking sheet and tear any big leaves in half. Use a towel to sop up any remaining bits of water.
Preheat the oven to 325 degrees. Drizzle the olive oil and salt over the top, then mix and rub with your hands to make sure every single leaf is thoroughly coated. Spread the kale out in an even single layer and bake in the oven for about 20 minutes. Keep an eye on them while they bake. They're done when the leaves are totally crisped throughout.
Cool and serve. Humidity is the enemy of kale chips, so their shelf life will depend on the weather. Store in an air-tight container at room temperature for up to a few days. If they become soggy, they can be recrisped in a 300 degree oven for about 5 minutes, and they'll be as good as new.