Start by cooking the peeled parsnip for 5 minutes in boiling water, then remove and put in cold water. Cut into pieces and marinate with the balsamic and olive oil. Meanwhile, peel the asparagus stalks and blanche for 2 minutes in hot water. Cut the pumpkin into long wedges and bake in oven for 5 minutes with some thyme and garlic for flavour. To serve, place the cooked parsnips, pumpkin and asparagus in a salad bowl and dress with olive oil and crushed peppercorns. Dress with the rocket leaves and sunflower seeds if using, before serving.