In a bowl mix together spring onions, carrot and garlic. Sieve in the cornflour then season with salt and pepper.
Grate the potatoes onto a clean tea towel and squeeze out any excess liquid. You may need to do this more than once. When dry to touch, tumble the into the bowl of ingredients. Add the egg and mix well.
Add the oil to the frying pan, when hot add spoonfuls of the potato and carrot mixture – flatten gently with the back of the spoon. If you want to be a little ‘chef-y’ feel free to use a cookie cutter to help shape them.
Don’t overload the pan, around 2-3 at a time. Fry until golden and crispy on one side before flipping over. Drain on kitchen paper.
Mix all dip ingredients together until ready to use.
To use for school lunches, leave to cool in the fridge, then pop the rosti in a lunchbox with a side of dip. Chunks of fresh cucumber and a little wedge of cheese will create a great snack.