Use a blender or food processor to combine all the ingredients except the olive oil. Slowly drizzle the olive oil in as you’re blending until the dressing emulsifies and becomes creamy in appearance. Taste, adjust with more salt and/or vinegar and set aside.
Combine the quinoa, red onion, arugula, cashews, cucumber, and chickpeas in a large bowl. Drizzle with about ½ cup of the ginger-curry dressing. Toss well, and then toss more. Sprinkle the feta across the salad and gently toss to distribute throughout. Serve at room temperature with fresh herbs added at the last minute.