Wash the cucumber and cut it into long, thin strips that are approximately as wide as a slice of smoked beef. Cut or chop the fresh chives very finely. Mix the chives through the cottage cheese and season this mixture generously with freshly ground black pepper.
Lay the slices of lean smoked beef flat and neatly spread out next to each other on a clean cutting board. Spread a full tablespoon of the seasoned cottage cheese mixture in the middle of each slice of meat. Next, place a prepared cucumber strip on the cheese layer of each slice.
Fold an edge of the meat over the cucumber and cheese and then roll the smoked beef slices as tightly as possible. Press the ends gently so that the rolls maintain their shape well and the filling stays in place.
Place the finished smoked beef rolls next to each other on a plate to serve immediately. If you want to save them, place them neatly in a well-sealed container and put them in the refrigerator to take them along later as a protein-rich snack.