Preheat oven to 300°. Rinse kale and thoroughly blot dry with a kitchen towel. Tear leaves from ribs; discard ribs. Tear leaves into 4-in. pieces. Pour oil into a large bowl, add kale and salt, and toss to coat evenly.
Arrange leaves in a single layer on 2 rimmed baking sheets. Bake, switching pan positions after 13 minutes, until leaves are crisp but not browned, 5 to 7 minutes more.
*You can use larger bunches, but you'll need more oil and seasonings and maybe a third pan.