Slice the cucumber into strips with a peeler, array the strips overlapping. Hard boil the eggs and smush with mayonnaise and pepper. Slice avocado thinly into oblongs. Lay egg on strips, add slices of salmon and avocado. Roll from end as tightly as ingredients will allow. Slice middle and make rounds slicing outwards. Refrigerate and mop up any juices. Serve within 30 minutes.