Heat the oil for the sweet potato bake in a large non-stick frying pan and fry the onion over a low heat for 8–10 minutes, stirring occasionally until soft. Add the garlic and thyme and cook for a further minute. Preheat the oven to 200°C/fan 180°C/ gas 6. While the onion is cooking, peel and thinly slice the sweet potatoes. Arrange a layer of the potatoes over the bottom of a 1.5 litre shallow ovenproof dish. Spoon a third of the sautéed onion and garlic over the top. Add another layer of potatoes and then some more onions. Repeat the layers ending with a final layer of sweet potatoes. Pour over the stock and season with freshly ground black pepper. Cover the dish with foil and bake in the oven for 30 minutes. Remove the foil and cook for a further 10–15 minutes or until the potatoes are tender and lightly browned around the edges. Just before the potatoes are ready, place a non-stick frying pan over a medium-high heat. Tip the hazelnuts onto a board and cut in half. Shake into the pan and toast for 1-2 minutes until lightly browned, stirring regularly. Put the rocket in a bowl and toss with a good pinch of salt, some freshly ground black pepper, 1tsp of the balsamic vinegar and half the olive oil. Add the hazelnuts and toss lightly. Using a slotted spatula, divide the potato bake between four plates, draining off any excess liquid as you go. Top each portion with the salad and drizzle with the remaining oil and balsamic vinegar. Serve immediately. See more Vegan recipes *Some vegan products may only be available in limited stores.