1. Mix together the carrot, parsnip, cumin and half the coriander. Season well, then stir in the flour and then the egg. Combine well and divide into 8 flat patties.
2. Put a little rapeseed oil in a large frying pan and fry the patties in 2 batches for 2-3 minutes on each side until golden in colour.
3. Meanwhile, make the sauce by heating the oil in a medium saucepan and frying the onion for 4-5 minutes until golden. Stir in the garlic and cook for 1 minute. Add the tomatoes, Worcestershire sauce and 100ml water. Simmer for 6-8 minutes to give a thickened but chunky sauce. Season and stir in the remaining coriander. Serve with the rosti.