Combine mustard, olive oil, vinegar, beef stock, sugar, salt and pepper
into a bowl and whisk well. This is your dressing. Peel and
slice the precooked knockwurst into strips. Cut onion into thin rings.
Dice the boiled potato. Slice the pickle thinly. Place
knockwurst, onion, potato, and pickle in large bowl. Pour dressing over
salad and toss gently. Refrigerate 2 hours. Peel and thinly slice egg; mix
with salad. Serve on lettuce leaves with a side of rye bread.