Preheat the oven to 392°F/200°C, then cut the cauliflower into small florets and prepare the sauce by mixing the pesto and mustard in a small bowl.
Brush the cauliflower florets with the sauce and place on a foil-lined baking sheet, then in the oven for 30 minutes.
Meanwhile, prepare your polenta according to the instructions on the packet.
Place on plates, then add cauliflower florets, diced avocado, and pomegranate seeds. Sprinkle with flax seeds, season with salt, pepper, a few sprigs of dill, and a drizzle of olive oil, then enjoy!