FOR THE DRESSING: Put the ingredients into a small jar with some salt and pepper, put the lid on an schake to comine, or whisk together in a jug to emulsify.
Quarter and core the apples. Cut each quarter into a few slices and place in a large bowl. Slice the potatoes slightly more thickly and add to the wowl, along with the onion.
Add the dressing and toss gently before transferring to a serving bowl or individual plates. Finish with a scattering of salt and pepper an, if using, some fronds of dill or fennel. Serve with brown bread or rye bread and butter.
total time: 10 minutes without boiling and cooling the potatoes. preparation time: 5 minutes