For the Beet Merguez Filling: In a medium skillet, heat rice bran oil over medium heat, then sauté onions and garlic until lightly caramelized and translucent, 5–7 minutes. In a food processor, combine the cooked onions and garlic with half the brown rice and purée until it forms a tacky paste. Set the paste aside. Add the cooked beets to the food processor, and pulse until they take on a coarsely ground texture, ensuring that the mix doesn’t become too fine. In a large mixing bowl, combine the pulsed beets with the remaining rice, rice paste, quinoa, rice flour, potato starch, paprika, and harissa spice. Mix until well combined and season with salt to taste. Reserve in the refrigerator until needed.
For the Stuffed Collard Greens: Preheat an oven to 375°F. Bring a large pot of water to a boil. Fill a large bowl with ice water. Season the boiling water generously with salt. Blanch the collard green leaves in small batches for 2–3 minutes, placing directly into the ice bath afterward. Remove the greens from the ice bath when cool and trim the stems down to where the leaves begin, removing any thick ribs that may impact the rolling process.
Divide the merguez filling into 24 balls and gently roll each into an oblong shape. Place one oblong merguez ball on the center of each collard green leaf. Fold the edges of the leaves towards the center and roll upward from the bottom—they should look like dolmas, or stuffed grape leaves. Place the rolled collard greens, seam-side down, in an even layer in a large baking dish or Dutch oven.
In a medium saucepan, heat oil over medium heat. Sauté onions and garlic until translucent. Add crushed tomatoes and chopped rosemary, cooking for 10–15 minutes to make a simple tomato sauce.
Top the stuffed collard greens with a drizzle of olive oil and the tomato sauce. Bake the greens, covered, in the oven for roughly 30 minutes or until the starches in the merguez have cooked through.
For the Sunflower Seed Dukkah: Lightly pulse the toasted sunflower seeds in a food processor to make a very coarse blend of broken seeds and finer particles. In a mixing bowl, stir the pulsed seeds with the remaining dukkah ingredients. Store in an airtight container at room temperature.
To Assemble: Top the baked, stuffed collard greens with the sunflower seed dukkah and a light drizzle of extra-virgin olive oil. Garnish the dish with mustard blossoms and serve as-is or alongside a simply dressed green salad.