1. Preheat your oven to 350°F (180°C) on the broil setting.
2. In a bowl, pour the cottage cheese and generously season with pepper.
3. Pour in the liquid sour cream and whisk everything together.
4. Set aside in the refrigerator.
5. Bring water to a boil in a saucepan.
6. Reduce the heat and add the eggs to cook for 10 minutes at a gentle simmer.
7. Cool them in cold water after cooking and peel them.
8. Meanwhile, sort the beet or watercress sprouts. Cut off the stems. Wash and dry them.
9. Cut the buns in half.
10. Place them with the cut side facing up under the broiler for 2 minutes, then let them cool on the rack.
11. Butter the bottom part of the buns generously with the sour cream/cottage cheese mixture, then add some beet sprouts, half a slice of chiffonade smoked salmon, and a quarter of the sliced egg.
12. Season with salt and pepper.
13. Add some more lettuce and cover with the second half of the bun.
14. Enjoy immediately.