Lightly oil a large pan. Sauté the bacon and onion for 1-2 minutes. Then add the potatoes and scallions and continue to cook for a few minutes until the potatoes are warmed through and are beginning to brown. Stir in the mustard and vinegar and season to taste - keep warm. To Poach the Eggs: Bring a large pan of water to simmer. Season the water with salt and a dash of vinegar. Break the eggs, one at a time, onto a saucer then slide gently into the water. Cover the pan and continue to simmer for 2-3 minutes or until the eggs are cooked to your liking.
Divide the potato mixture onto four plates. Lift the eggs with a slotted spoon from the water and drain well. Place the poached eggs on top of the potato mixture. Sprinkle with black pepper. Serve with mixed leaves or a vegetable of your choice.