Walnuts and lemon zest pair nicely with kale in this super simple pesto. Steaming the greens in the microwave eliminates the hassle of blanching and means less moisture to squeeze from the greens. For nut-free pesto, replace the walnuts with pumpkin seeds. For dairy-free pesto, use nutritional yeast in place of the parmesan.
Transfer kale to a large microwave-safe bowl and microwave on high until soft and bright green, about 3 minutes. Remove from microwave and set aside to cool.
Once the kale is cool enough to handle, using your hands squeeze out as much liquid as possible. There may not be much.
In a food processor, pulse the squeezed kale until it is roughly chopped (3-4 pulses).
To the food processor, add the lemon zest, grated garlic, walnuts, parmesan and salt. Process until a coarse paste results.
Open the feed on the food processor. With the processor running, stream in the olive oil. Taste and adjust salt as needed.