Cut the carrots and parsnips lengthwise into batons. Chop the sweet potato into chunks, halve the new potatoes, and slice the red onion into wedges. Leave cherry tomatoes whole if using.
2½ lbs mixed root vegetables
Preheat the oven to 400°F (200 °C) or 350°F (180 °C) fan.
Add the chopped vegetables, new potatoes, cherry tomatoes, onion wedges, and whole garlic cloves to a large roasting tray. Nestle the rosemary and thyme sprigs among the veg. Drizzle with 2 tablespoons of olive oil, season with salt and pepper, and toss everything together until well coated.
Place the tray in the oven and roast for 45 minutes, or until the vegetables are golden and tender.
Once the vegetables are done, remove the garlic cloves from the tray. Squeeze the soft roasted garlic into a small bowl. Add the olive oil, chopped parsley, lemon juice, salt, and pepper, then whisk or blend until smooth.