1.Preheat oven to 200°C (180°C fan-forced). Line two oven trays with baking paper.
2.Combine celeriac, pumpkin and capsicum in a bowl with oil, garlic and thyme. Season with sea salt and freshly ground black pepper; toss to coat vegetables in oil mixture. Spread the vegetables over prepared trays and bake for about 40 minutes or until tender.
3.Meanwhile, place the barley in a medium saucepan with the water and salt; bring to the boil. Simmer, uncovered, for about 30 minutes or until the barley is tender. Drain. Add the barley to the trays; bake for a further 5 minutes.
4.To make a dressing, combine the extra virgin olive oil and juice in a small bowl; season to taste with salt and pepper.
5.Add the broccolini to a large saucepan of boiling salted water; return to the boil. Drain broccolini; place onto a large serving platter. Add the vegetable mixture and parsley. Drizzle with dressing.