To make the rosemary vinaigrette, place the oil, vinegar, mustard, garlic and rosemary in a screw-top jar. Shake until combined. Set aside to develop the flavours.
Preheat oven to 180°C. Spread the hazelnuts over a baking tray and bake for 7 mins or until golden. Transfer to a clean tea towel and rub to remove the skins. Coarsely chop.
Meanwhile, heat a barbecue grill or chargrill on medium-high. Drizzle plum with oil and toss to coat. Cook, turning once during cooking, for 4 mins or until plum softens slightly and cut sides are charred. Transfer to a plate to cool.
Remove and discard the garlic and rosemary from the rosemary vinaigrette. Arrange the rocket, prosciutto and goat’s cheese on a serving platter. Top with plum and drizzle with rosemary vinaigrette. Season with pepper and sprinkle with hazelnut to serve.
