Cook and Drain Pasta: Cook the medium shell pasta according to package directions in a large pot of salted boiling water. Once cooked to al dente, drain thoroughly and rinse under cold water to cool and prevent sticking. Drain very well again.
Prepare Dressing: In a large bowl, whisk together the drained sweet pickle relish, garlic powder, celery seed, mayonnaise, sour cream, granulated sugar, yellow mustard, and apple cider vinegar until the dressing is smooth and well combined.
Combine Ingredients: Add the cooled, drained pasta, chopped hard-boiled eggs, chopped celery, chopped sweet onion, drained pimentos, and chopped green bell pepper to the bowl with the dressing. Stir gently but thoroughly to ensure all the ingredients are well coated.
Season and Chill: Season the pasta salad to taste with Kosher salt and freshly ground black pepper. Stir once more to distribute seasonings. Cover the bowl and chill the salad in the refrigerator for at least 1-2 hours (or longer for best flavor development) until ready to serve.
Enjoy this delightful Amish Pasta Salad at your next gathering or as a refreshing side!