Chips: Put an oven rack in the center of the oven. Preheat the oven to 350 degrees F.

Remove the thick stem from the kale and discard. Cut the leaves into 2 to 3-inch pieces. Put them in a bowl and drizzle with olive oil. Toss well. Arrange the kale in a single layer on parchment paper-lined baking sheets. Bake for 10 to 12 minutes until crispy and slightly dark on the edges. Season with salt and pepper, to taste.

Using a mandoline slicer or a sharp knife, slice the white potatoes and the sweet potatoes into 1/8-inch thick slices. Put them in a bowl and drizzle with olive oil. Toss well. Arrange in a single layer (without overlapping) on parchment-lined baking sheets and bake for 12 minutes. Turn the slices over and continue to bake, checking every 2 minutes until brown and crispy, about 6 to 8 minutes longer. Season the chips with salt and pepper, to taste.

Mayonnaise: In a small bowl, combine the mayonnaise, lemon juice and lemon zest. Season with salt and pepper, to taste.

Transfer all the chips to a large bowl and serve with the mayonnaise.

Cook's Note 1: Some potato chips will cook faster than others. Remove the chips from the baking sheets as soon as they become brown and crispy.

Cook's Note 2: The recipe can be doubled or tripled.