Heat oven to gas 200 C / Gas 4. Put the carrots, butternut squash, parsnips and sweet potato on a baking tray and drizzle with a little olive oil. You can add whole peeled garlic cloves if you want. Roast them until the vegetables are golden, about 30 mins.
Heat some olive oil in a deep stock pan and fry cumin seeds and red chilli flakes on slow heat until you smell their aroma (be careful not to burn them).
Add chopped red onions, ginger and crushed garlic into the pan and fry until onions are slightly caramelized.
Add chopped celery and fry for a few minutes then add roasted vegetables into the pan. Carry on frying them on medium heat.