1. In a large pot cook all the vegetables except the onion until tender.
2. Peel potatoes, put them in a large bowl and mash into puree. Add egg and mix until incorporated.
3. Chop an onion and sauté over medium-low heat, stirring occasionally until golden.
4. Dice carrots, sweet potato, roughly chop cauliflower. Add to the bowl. Add cooked onion. Season with salt, pepper and turmeric. Mix well.
5. Heat oven to 200c (390f).
6. Heat oil over high heat in a large over-proof pan. Transfer potato mixture to the hot pan, flatten and cook for about 5 minutes. After 5 minutes transfer to the oven and bake for 45 minutes or until golden brown.
7. Let cool and carefully flip.