Preheat oven to 350° F
Tear leaves into 1½-inch pieces and blot dry with a paper towel. Leaves must be dry to be crispy.
In a large bowl, combine vinegar or juice, oil, and salt. Mix well. Add kale in batches and use your hands to massage leaves with oil and seasonings.
Arrange kale pieces in a single layer on a parchment-lined baking sheet. Bake10 minutes, flip and bake for another 5 minutes or until crispy. Baking times may vary. Check often so they don’t burn.
Let cool and serve. Can be stored in an airtight container in the refrigerator for up to 5 days.
VARIATION #1: Add 1 teaspoon of your favorite seasonings to the bowl with oil and vinegar or juice. Optional seasonings are ground cumin, garlic powder, onion powder, chili powder, smoked paprika, dried oregano, dried basil, curry powder, or your favorite spice mix.
VARIATION #2: For a sweet version add 2 tablespoons honey or maple syrup to the seasoning mix.