Chop shrimp into small chunks (about ½ an inch) and combine in a large bowl with the celery, onion and lemon zest. In a food processor or blender, pulse together the egg yolk, vinegar, dill, cayenne and salt. While the blender is running, slowly pour in the oil until the mayo is thick and creamy. Taste for seasoning. Fold ½ cup of the mayo into the shrimp salad and stir to combine. Add more mayo if desired. Add in the juice of the lemon and a dash of salt and pepper to taste. Serve on a salad, crackers or a crusty loaf of bread and enjoy! Keeps in the fridge for 2-3 days.