Preheat oven to 375° F. Line a baking sheet with parchment paper.
Combine 3 tablespoons of the ground flax with the sesame seeds and set aside.
In a high speed blender or food processor, grind the walnuts into a coarse meal. Add in the remaining ingredients with exception of the lemon/lime juice and blend everything until well combined, scraping the sides as needed. You want to keep the mixture somewhat chunky so don’t over blend.
Add the spinach to the food processor and combine well. If the mixture is too moist to handle, add some oat flour 1 tablespoon at a time (or alternatively some ground flax meal).
Form falafel using your hands, then roll each ball in the flax and sesame seed coating. If that isn't working, you can use a tablespoon or cookie scoop and drop a ball into the flax/sesame mixture...then roll to coat. Place them on the baking sheet.
Bake for 15 minutes, turning every 5 minutes to achieve even color. Drizzle a small squeeze of lemon or lime juice on the top.
We love these warm, paired with hummus or babaganoush, served on top of salads, in corn tortillas for ‘falafel tacos,’ wrapped in green leaves or just as a straight up snack.