Lay your summer squash on a sturdy work surface tilting it up at an angle.
Using a vegetable peeler, slice down the summer squash, creating ribbons, rotating until you’ve used as much of the squash as you can. (Save remaining pieces for dipping in extra pesto.)
Add the ribbons to a colander and let sit in a sink or over a plate while you prepare the pesto. Some of the excess water in the summer squash will drain.
Combine the chard leaves, mint leaves, half of the olive oil, sunflower seeds, lemon juice, garlic, salt and pepper in a blender and pulse a few times to combine the ingredients. Remove the lid and use a spatula to scrape the pesto back down into the bowl.
Replace the lid and turn the blender on, whizzing the pesto while slowing drizzling the remaining cup of olive oil until blended into a thick, smooth consistency.
Transfer the summer squash ribbons to a serving bowl and toss with the pesto. Serve immediately or chill and serve cold.
Store leftovers in a lidded container for up to 24 hours.
How to Freeze (Any) Pesto:
Transfer pesto to an ice cube tray and freeze. Once frozen, transfer pesto cubes to a ziplock bag and freeze for up to 1 year, defrosting a cube at a time as needed. F