In Germany, this kind of Herring salad is traditionally offered at New Year's Eve parties, with the leftovers served on New Year's Day.
First, prepare the marinade:
1/2 cup olive oil
1/3 cup balsamic vinegar
1 tsp salt
1/2 tsp black pepper
1 tsp cane sugar
2 tsp herbes de provence
1 large onion, diced
Mix the ingredients well, then set it aside.
Next, mix the remaining ingredients in a large bowl:
10 soused herring halves (lightly pickled, "Matjes" style)
1/2 lbs cooked potatoes, peeled and diced
1 jar of pickled red beets, diced
Optional: 1/2 lbs pork loin, pan fried & diced
5 hard boiled eggs, diced
1 apple, diced
1/2 lbs Swiss cheese, finely diced
1/2 cup walnuts, finely diced
1 small jar of capers
1/3 lbs sour cream
1/2 bunch of chives, chopped
1/2 bunch of dill, chopped
Finally, add the marinade, mix everything together, and put it in the fridge for at least 6 hours before serving.