Preheat the oven to 190°C.
Peel the parsnips and cut into pieces roughly 5cm long and 1.5cm wide. Peel the onions and cut into 6 wedges.
Place parsnips and onions in a large mixing bowl and add 120ml of the olive oil, the thyme, rosemary, garlic and 1 teaspoon of salt. Mix well and spread out in a large roasting tin. Roast for 20 mins.
While the parsnips are cooking, top and tail the sweet potatoes. Cut them widthways in half, then each half into six wedges. Add to the roasting tin and stir well. Return to the oven and roast for a further 40-50 mins.
When all the vegetables are cooked through and have taken on a golden colour, stir in the halved tomatoes. Roast for 10 more minutes.
Meanwhile, whisk together the vinaigrette ingredients with the remaining 2 tablespoons of oil and season well.
Pour the dressing over the roasted vegetables as soon as you take them out of the oven. Stir well and season to taste. Scatter the sesame seeds over the vegetables and serve at the table in the roasting tin.
4 red onions
150 ml olive oil
4 thyme sprigs
2 rosemary sprigs
1 head of garlic, halved horizontally 2 Sweet potatoes
30 cherry tomatoes, halved
1 tablespoon sesame seeds, toasted
For the vinaigrette:
2 tablespoons lemon juice
4 tablespoons capers, roughly chopped
1/2 teaspoon maple syrup
1/2 teaspoon dijon mustard
Salt and pepper