Klaus`s heringsalat (klaus`s herring salad)

Contents of one 8 oz. jar of pickled herring, drained, diced in bite size pieces (keep herring juice for dressing!)
1 medium size Golden Delicious apple (no more than 8 oz.), cored, peeled, diced
1 small onion (about 2 oz.) trimmed, peeled, chopped finely
1 sweet sour pickled cucumber, chopped finely
1 hard boiled egg, shelled, chopped
2 either red or yellow Yukon Gold type potatoes (about 1/2 pound), steamed with their jackets on, peeled, sliced
1 small leafless red beet (about 1/2 pound), steamed, trimmed, peeled, OR the contents of one 8 oz can of beets,
drained and diced
1 Tablespoon mustard
1-2 Tablespoons Quark
1 Tablespoon fresh dill (about 1 young stem) minced
salt (about 1/4 teaspoon, or to taste)
freshly ground white pepper (about 1/8 teaspoon, or to taste)

In a medium size bowl combine herring pieces, apple, onion, pickled cucumber, hard boiled egg, red beet and potatoes. In a separate bowl blend mustard, quark, salt, pepper, 2-3 Tablespoons herring juice and fresh dill to make a dressing. Pour dressing over salad and toss. Serve with rye bread.