In a serving bowl, whisk together the sour cream, mustard, parsley, bacon, and salt and pepper, to taste. Add the potato, shrimp, and celery. Toss everything together until it is all coated with the dressing and serve.
Put the potatoes into a large pot and cover with cold water. Bring to a boil over medium heat and add a generous pinch of salt. Cook for 8 minutes so they are tender but still slightly firm. Strain and let them cool. When they are cool, cut them in half and carefully scoop out the insides using a teaspoon or melon baller to form a cup.
Preheat the oven to 400 degrees F.
Put the potato cups into a large bowl, add the oil, rosemary and season with salt and pepper, to taste. Carefully toss the potato cups to coat them with the oil. Arrange the potatoes, cut side up, on a baking sheet and bake until the cups are browned and crisp, about 15 to 20 minutes.
While the potatoes are baking, put the bacon into a cold skillet and cook over medium heat until crisp. Drain the bacon well on a baking sheet lined with a brown paper bag. (Reserve 2 pieces of bacon for Round 2 Recipe Shrimp and Potato Salad with Sour Cream and Bacon Dressing.) Chop the remaining 6 pieces.
In a bowl stir together the sour cream, mustard, 1 tablespoon chives, the chopped bacon, and salt and pepper, to taste. Arrange the potatoes onto a serving plate and fill each with a spoonful of the sour cream and bacon mixture. Garnish with the remaining chives and serve immediately.
Peel the length of each cucumber to form alternating stripes of unpeeled and peeled. Cut the cucumbers into 12 (3/4-inch) pieces. Scoop out the center using a teaspoon or a melon baller, leaving the bottom and sides intact to form a cup. (Reserve the centers for the Round 2 Recipe Chicken Tacos with Cucumber Salsa.) Turn them upside down onto a towel and let them drain while you make the filling.
Bring a medium pot of salted water to a boil over medium heat. Add the shrimp and cook until bright pink, about 3 to 4 minutes. Strain and rinse in cold water. Remove the shells and discard. (Reserve 12 shrimp for the Round 2 Recipe Shrimp and Potato Salad with Sour Cream and Bacon Dressing.)
Chop the shrimp into small pieces and put them into a bowl. Add the horseradish, lemon juice, salt and pepper to taste, half the can of tomatoes (reserve the remaining half for the Round 2 Recipe Chicken Tacos with Cucumber Salsa) and 1 tablespoon of parsley. Evenly divide the shrimp mixture between the cucumber cups. Arrange them on a serving platter and garnish with remaining parsley.