Boil and peel the quail eggs in advance. Rinse vegetables with cold water. Peel the onion. Drain the brine from the canned mussels.
Prepare the vegetables. Cut the onion into half rings. Chop the dill with a knife and tear the salad into small pieces with your hands. Place prepared ingredients into a bowl. Cut the cherry tomatoes into quarters, and cut the cucumber into semicircular slices. Place all ingredients in a salad bowl and mix.
Assemble the salad. Add pickled mussels to the prepared vegetables. Cut the prepared eggs into halves and add to the rest of the ingredients.
Dress the salad. Mix lemon juice, olive oil, salt, pepper, Worcestershire sauce and sugar. Mix everything well and taste to adjust the amount of salt and pepper. Season the salad with the resulting sauce and leave it in the refrigerator for 5 minutes.
Place the finished salad with canned mussels in a salad bowl or place portions into small glasses.