Boil the diced potatoes and carrots in salted water until tender but not mushy, about 10-15 minutes. Drain and cool.
If raw, cook shrimp in boiling salted water for 2-3 minutes until pink. Drain, cool, and chop.
Hard-boil the egg for 10 minutes, cool in ice water, peel, and dice.
In a large mixing bowl, combine the cooked potatoes, carrots, egg, pickles, peas, and chopped shrimp.
Stir in the mayonnaise, coating all ingredients evenly. Add salt and pepper to taste.
Cover and refrigerate for at least 1 hour for the flavors to meld. Garnish with dill and whole shrimp if desired before serving.
