Line a baking sheet with a silicone mat. If you don't have one, you can use foil, but be sure to spray lightly with cooking spray to prevent sticking.
In a medium bowl, combine the walnuts, maple syrup, and salt. Toss together until the maple syrup has evenly coated the walnuts. Dump the coated walnuts on prepared baking sheet and spread them out. Bake the walnuts for 7-10 minutes.
While the walnuts bake and cool, whisk together the dressing ingredients in a small bowl. Set aside.
In a large bowl, combine the cooled quinoa, walnuts, pomegranate, spinach, and feta cheese. Add 1/2 of the dressing and stir to combine. Taste and add more dressing, 1 Tbsp at a time, as desired.
Store prepared salad in an airtight container in the refrigerator.