Finding ways to use as much of your ingredients as possible is a great way to reduce your food waste and get the most for your money. You can do this by adding both the stems and leaves from leafy greens to sauces like pesto.
Image from llstalteri
By boiling the steams of leafy greens -- like the woody ones in kale or chard, or those thick broccoli stems -- you can soften them enough to use in a delicious pesto. If you want, you can even use the leaf, too.
I've used green chard in a pesto when I've run low on basil and needed something to add volume without impacting the flavour too much. If you don't eat pesto often, you can always use up your vegetables by making a simple stock