In a 10 inch skillet, cook the bacon on medium heat for 5 minutes then add the green onions and cook for an additional 3 minutes. Using a slotted spoon, transfer bacon and green onions to a bowl and set aside. Melt the butter in the skillet.
Peel and spiral cut the potatoes. Squeeze out any excess water. Add the bacon mixture and the butter from the skillet to the potatoes and mix well.
On medium heat, add the potato mixture and flatten it with a spatula. Cook for 12-15 minutes until the bottom is golden brown and crispy. Flip over the rosti and cook for an additional 10 minutes. Transfer the rosti to a cutting board and cut into quarters.
Crack an egg into a ramekin.
Bring a pot of water to a simmer and add 2 TBSP of white vinegar. Using a spoon, create a vortex in the water and carefully slide an egg into the center so that the vortex will help wrap the whites around the yolk. Cook for 2-3 minutes and make sure the egg doesn’t stick to the bottom. Remove egg using a slotted spoon and place onto a paper towel-lined plate. Repeat for the other eggs.
To serve, put two rosti quarters on a plate. Top each rosti with 2oz of the gravlax, poached egg, and pour over a generous amount of hollandaise sauce. Garnish with smoked paprika and dill.