Grate the potatoes into a bowl. Squeeze to remove excess water if needed.
In a large bowl, combine the cooled mash potato and add the grated raw potato and half of the sage.
Season well with salt and pepper and stir to create a soft dough. Add some flour to help stiffen the mixture if needed.
Heat some oil and half of the butter in a pan over a medium to low heat, form and shape thick discs of the potatoes mixture and lightly press on the pan to make sure it is sticking together.
Cook for 3 -4 minutes until the base of the boxty is golden brown. Flip over and add the rest butter and the rest of the sage.
Continue cooking for a further 3 – 4 minutes depending on the thickness until the boxty are piping hot in the middle, basting with the foaming butter.
In the meantime, in a saucepan with boiling water a a drop of lemon juice or vinegar. Once simmering, drop the eggs and poach for 2 minutes or so.
Remove the boxti from the heat, and place onto serving dishes. Add the bacon and the poach egg on each boxti , and spoon some hollandaise sauce over. sprinkle some fresh herbs and a sprinkle of Sea salt and pepper if desired.
Enjoy immediately.
