1. Combine mayonnaise, sour cream, parsley, chives, garlic, salt, and pepper in a blender or food processor.

2. Blend until smooth then refrigerate for at least 30 minutes at 4°C (40°F) to allow the flavors to meld.

3. Slice the endive and cucumber into thin strips about 3mm (1/8 inch) thick.

4. Cut the salad onions into thin wedges about 1cm (1/2 inch) wide.

5. In a large bowl, combine the sliced endive, cucumber, and salad onions.

6. Toss gently to combine.

7. Add 450g (1 pound) of shrimp to the bowl and toss gently to coat with the dressing.

8. Cover the bowl with plastic wrap and refrigerate for at least 30 minutes at 4°C (40°F) to allow the flavors to meld.

9. Just before serving, garnish with fresh dill.

10. Serve with crusty bread, if desired.