For marinade combine beetroot puree with orange zest, salt, and black pepper powder in a plate. Mix well. Marinate the basa fish pieces. Heat oil on a tava. Shallow fry the marinated fish pieces on both sides. Transfer the fish pieces to a plate. For the cauliflower sauce, heat unsalted butter in a pan. When the butter melts add cauliflower florets, salt, and black pepper powder. Mix and cook well. Horizontally cut the bread loaf to make a slice. Place the rocket leaves on this bread slice. Spread the cauliflower sauce on the leaves. Top with the fried fish pieces. Drizzle beetroot puree and cauliflower sauce on the fish. Garnish with parsley leaves.