Preheat oven to 275°F. Line two non-insulated baking sheets with parchment paper. (The parchment is optional but helps with cleanup and guarantees no sticking.)
Wash kale and pat or spin dry. With leaves folded in half, with a knife or kitchen shears, cut out tough center ribs, then tear leaves into bite-sized pieces.
Place pieces in a large bowl and drizzle with the olive oil. With hands, toss to coat all leaves thoroughly with olive oil. Sprinkle on salt and toss leaves a few more times.
Lay leaves on baking sheets, opening up folded ones and rubbing some of the oil from the pan and your hands onto areas that weren’t covered. Place baking sheets on upper or middle rack in oven. Bake 20 to 22 minutes, removing pans from oven when leaves look mostly dry or if you see any browning.