Prepare the quinoa according to package instructions. Set aside to cool.
Chop the vegetables into 1-2 inch pieces. Transfer to a large bowl, add olive oil and seasonings, and toss to coat.
Spread vegetables on a large rimmed baking sheet; roast at 400° for 30 minutes, flipping halfway through.
While the quinoa and vegetables are cooking, prepare the sauce by combining the Greek yogurt, mayo, honey, dijon mustard, and cayenne pepper in a small bowl. Whisk well using a small whisk or fork.
Using two large shallow bowls, layer the mixed greens, roasted veggies, and quinoa. Add the hard boiled eggs, drizzle with sauce as desired, and sprinkle the hemp hearts on top. Note: this recipe makes 2 bowls, so if you don't plan to make them both right away, save half of the ingredients in the refrigerator for another day.