Preheat oven to 400 degrees F. Line a large baking sheet with parchment paper and set aside.
Set up a station with 3 large bowls. In the first bowl sift together the brown rice flour and all purpose flour. In the second bowl, beat together the 3 eggs. Finally, in the last bowl add the panko bread crumbs with a generous pinch of salt and pepper.
Working in batches place some of the washed and still wet cauliflower in the flour bowl first. Toss to coat. Pick up the cauliflower (hands work best here) and shake off any excess flour. Gently place the coated cauliflower in the egg and toss to coat. Finally (again, hands work best), pick up the cauliflower and coat with the panko breadcrumbs.
Place each cauliflower floret on the prepared baking sheet in a single layer. Repeat until all cauliflower has been coated and prepared.
Place the prepared cauliflower in the oven and bake for 15 minutes, or until the tops are slightly golden. Remove, flip the cauliflower and continue to bake an additional 5-10 minutes, or until golden all over.
Allow cauliflower to cool slightly before drizzling with sauce and topping with chopped green onion and cilantro, if desired.