To cook the bacon: Place the bacon in a sauce pan with the peppercorns, bay leaf and onion. Cover with cold water and a lid. Bring to the boil, turn the heat down and let simmer for 1¼ hours. Remove from the water and set aside to cool.
To cook the potatoes: Meanwhile place the potatoes in a large pan of salted water. Bring to the boil, then cover and simmer for 15–20 minutes, until the potatoes are tender without breaking up. Drain and return to the pan over a low heat to dry out for a minute or two.
To make the dressing: Place all the dressing ingredients in a jam jar. Season with a little salt and black pepper. Shake the jar to mix the ingredients. Stir a tablespoon of the dressing through the warm potatoes.
Place the eggs in a saucepan of cold water and bring to the boil. Reduce the heat to simmer. Cook for 5 minutes. The yolks will be a bit runny at this stage, if you like them cooked through, increase the time to 7 minutes. Remove from the heat and run under cold water to stop the cooking process. When the eggs are cooled but are still warm, peel off the shells and cut into quarters.
When the bacon is cool enough to handle, trim away the skin and any fat and discard. Using two forks shred the meat, set aside.
Place the leaves, red onion and mange tout in a bowl. Add a tablespoon of dressing and mix well. Divide between four dinner plates or bowls. Top with the potatoes, shredded bacon and eggs. Drizzle over some more dressing and sprinkle on some nigella seeds.
Serve with crusty bread.