Remove kale leaves from the stems and tear into bite-sized pieces—kind of like large potato chips. If using collards, cut the leaves away from the stems and use kitchen shears to cut the leaves into approximately 2-inch squares or strips.
Rinse the torn or cut leaves, and—this is extremely important—let it dry completely. Damp kale will make for soggy chips that don’t bake evenly (I learned this the hard way). Use a salad spinner, or spread on kitchen towels and let it dry as long as need be.
Once the kale or collards are dry, preheat the oven to the desired temperature (as mentioned, 325º F. works best for me, but experiment and see what works best in your oven.).
Transfer kale or collards to a bowl and drizzle in a little olive oil. Massage it evenly into the leaves with your hands. If you’d like, you can add a tiny bit of red or white wine vinegar or apple cider vinegar and seasonings at this point. See suggestions below recipe box.
Spread the leaves on one or two parchment-lined baking pans, in a single layer. Bake for 12 to 20 minutes, depending on your oven’s true temperature. Check them from time to time. The chips should be evenly dry and crisp and just barely beginning to brown.
Remove from the oven and let cool until they can be handled. Carefully transfer to a serving bowl. At this point you can sprinkle in a little salt, but you may not need or want to if you’ve added other tasty seasonings.