First put a Pan with Water upon the stove. Add a pinch of Sea Salt to it. You will bring the Water to the Boil. Meanwhile peel the Potatoes before slicing them. Add the Potato Slices to the boiling Water. they will only take about 10 to 15 minutes for they are better a little al dente, with a bit of a bite.
Those minutes give the time needed to wash and slices the Radishes to place them in a Salad Bowl. Do the same for the Cucumber. Then chop the Dill and add it to the Bowl.
Finally you can hand made your Wholegrain Mustard Vinaigrette or use a shop bought one.
For hand made Wholegrain Mustard Vinaigrette: Use 100 ml of Vinegar either White Wine Vinegar or Cider Vinegar (I would recommend Aspall Vinegars). Add 300 ml of a good Virgin Olive Oil. Salt and Pepper, a minced Garlic, and the Most important A hipped Tablespoon of Ancient Grain Mustard, also, called Wholegrain Mustard. I use Dijon's ones for their flavoursome taste. Whisk and taste the Vinaigrette and adjust if needs be. If there is too much Vinaigrette, store some in the Fridge for another day.
Drain the Sliced Potatoes and let them cool for 15 minutes in the Fridge, for this side Salad is better served crispy cold.
During that time you can prepare your Main to be served with Side Salad. I love that Side Salad served with deboned Fillets of Grilled Mackerel. Once your Main is done. Finish of the Salad by taking all the elements out of the Fridge. Pace the Potatoes within the Salad Bowl. Add the Whograin Mustard Vinaigrette, then mix well but very gently the Salad Ingredients together. It will then be ready to serve with the Main. Finish off with more Dill upon the Main Course and slices of Lemons upon the plates. Enjoy.