Preheat the oven to 300 degrees F. Rinse the kale, then remove the stems and dry the leaves thoroughly with a clean kitchen towel or paper towel. Spread the leaves out on a baking sheet, then scatter the lemon zest on top. Bake until toasted, 15 to 20 minutes. Then, set aside to let cool completely.
Meanwhile, in a small skillet, toast the fennel seeds over medium heat until fragrant, 2 minutes. Coarsely crush in a mortar and pestle or in a bowl with a wooden spoon.
Using your hands, break up the cooled kale leaves into small pieces. Discard any big, woody pieces of stem.
In a medium bowl, toss the crushed kale with the fennel pollen, fennel seeds, and ½ teaspoon kosher salt. Season to taste with more salt. Store in an airtight container at room temperature for up to two weeks.