Preheat oven to 230°C fan forced. Arrange potatoes in a large greased roasting pan and spoon over 1 tablespoon oil. Season with salt and turn to coat. Roast for 30 minutes. Remove from the oven and turn potatoes over. Return to the oven for 10 minutes.
Add the Broccolini® to another roasting pan. Spoon over remaining oil and sprinkle with spice, turning to coat. Roast for 10 minutes on the shelf under the potatoes. Set both potatoes and Broccolini® aside to cool to room temperature.
Arrange the rocket and spinach on a large serving platter or board. Top with Broccolini, including spices from pan, potatoes and blackberries. Combine all the dressing ingredients and spoon over the salad just before serving. Serve.