Combine shrimp, celery, basil, olives, shallot, mayonnaise, vinegar and pepper in a medium bowl. Stir to combine.
Carefully hollow out the inside of each tomato using a melon baller or small spoon; reserve the scooped tomato for another use. To serve, fill each tomato with a generous 1/2 cup of the shrimp salad. Then garnish with chopped dill and capers.