Preheat the oven to 300F. Line an 8" x 8" square baking pan with parchment paper. (Double-check your pan size. A 9" x 9" pan won't work for this recipe.)
In a large mixing bowl, stir together the quinoa, millet, oats, blueberries, hemp seeds, and pepitas seeds.
In a small saucepan, whisk together the brown rice syrup, sunflower butter, coconut oil, flaxseed, vanilla, and sea salt over low heat until smooth, glossy, and caramel-like.
Pour the wet mixture over the dry, and stir well to evenly coat every last bit of the dry ingredients. This takes a bit of time and you almost need to press the wet mixture into the dry. If you're willing to get your hands dirty, use them to mix instead of a spoon (I recommend lightly greasing them with coconut oil to repel the stickiness).
Spoon the mixture into the lined pan. Place another piece of parchment paper on top, and use your hands to press and compact evenly into the pan. Discard the top layer of parchment paper.
Bake for 22 to 26 minutes, or until the surface is no longer tacky to the touch, the top is very light golden, and the edges are just beginning to turn ever so slightly deep golden. Be careful not to over-bake, or you'll end up with crunchy bars instead of soft, chewy ones.
Remove from the oven and let cool completely in the pan.
Grasp the edges of the parchment paper and lift the bar out of the pan. Slice and enjoy.
Store the bars in the pan loosely covered with foil at room temperature.