Pre-heat the oven on gas mark 7 and oil some baking trays.
Cut all the vegetables into large bite-sized wedges.
Blanch the parsnips (and carrots if you use them) in boiling salted water for 10 mins. Then drain and dry.
Toss all the vegetable pieces in the olive oil and sea salt and spread onto the baking trays with only a single layer of vegetables, and add the rosemary.
Bake on the top shelf for 45mins - 1 hour, turning occasionally and sprinkling with the balsamic vinegar halfway through cooking.