Whisk the mustard, lemon juice, balsamic and oil in a bowl, season with salt. Stir in the shallot and herbs.
Cook the potatoes in boiling water for approx. 25 mins. until soft. Drain the potatoes, peel while still hot, cut in half lengthwise, add to the dressing, mix and leave to cool. Set aside the peel.
Heat the oil in a frying pan. Fry the reserved potato peel and capers for approx. 5 mins. until crispy, stirring occasionally. Remove and drain on paper towels, season with salt.
Carefully lower the eggs into the boiling water, simmer over a low heat for approx. 7 mins. Remove, plate up the potatoes and salmon. Peel the eggs, cut in half, serve on top, garnish with the herbs and crispy potato peel.