Boil the potatoes in a pan of salted water for 15–20 minutes until soft. While the potatoes are cooking put the butter, milk and scallions into a small saucepan and cook until the scallions have softened. Grill 2 of the rashers until crispy, then chop into small pieces. When the potatoes are cooked drain well and mash. Then add in the warmed butter, milk and scallion mixture along with the parsley, mustard and rashers. Season with salt and black pepper. Leave to cool. When the mixture has cooled shape into 8 equal size rounds, chill in the fridge for half an hour. Place all Mojo Sauce ingredients in a food processor and blend till smooth. To poach the eggs: Bring a large pan of water the boil. Reduce to a gentle simmer and add the white wine vinegar and a little salt. Break two of the eggs into the water and simmer for 3-4 minutes until just cooked but still soft on the inside. Remove with a slotted spoon and drain well on kitchen paper. Repeat with the other two eggs. While the eggs are cooking take the potato cakes from the fridge and dust with a little flour. Heat the oil in a frying pan, add the potato cakes in two batches and gently fry for 2–3 minutes on each side until golden. Meanwhile grill the remaining streaky rashers.
Divide the potato cakes between four warmed plates. Add two rashers, a poached egg, a drizzle of the Mojo Sauce and a green salad.