Dressing: In a small jar add extra virgin olive oil, lemon juice, garlic, dijon mustard, sugar, 1/4 tsp salt and pepper. Tightly screw on the lid then shake to combine. You can also do this in a small bowl with a whisk. Place to one side and shake/whisk again just before needed.
Potatoes: Place potatoes in a large pot with enough cold water to just about cover them. Mix in 2 tsp salt then bring to a boil until the potatoes are fork tender (7 or so mins once boiling). Don't over boil them or they'll turn to mush. Drain (don’t rinse) and leave to steam dry for 5 mins, just to allow some of the water to escape.
Prosciutto: Meanwhile add 1/2 tbsp oil to a pan over low-medium heat. Add prosciutto (you may need to work in two batches) and fry both sides until deep golden and visibly crispy. Place one side, it'll crisp more as it cools, then dice into small shards. Leave the fat in the pan.
Combine: Turn off heat and allow oil to completely stop sizzling. You don't want to cook this salad, just keep it warm as you combine. Add potatoes, pour in the dressing then toss to coat the potatoes. Add in parsley, chives and dill and toss again. Add most of the prosciutto and give it all one final toss. Check for salt. The prosciutto and small amount in the dressing should provide enough, but adjust if needed.
Serve: Serve up warm with extra prosciutto crumbled on top.