Mix all the ingredients in a bowl. Cover and let stand an hour.
Grate the horseradish very finely in the whole cream. Mix and let stand in the fridge for a good hour.
Heat a pan with a drizzle of oil.
Using a tablespoon, take a little dough. Then put it on the hot pan to form a small circle (as you say my blinis are never round). As soon as a small bubble (hole) is formed (after 30s - 1 min of cooking) return and cook on the other side. Repeat until there is no more dough.
Cut the salmon heart into cubes. Put aside.
Pass the horseradish cream mix to the Chinese, put it in your chilled siphon with a cartridge, shake and test.
On each blini add a good spoonful of salmon dice. A little horseradish chantilly and some lumpfish eggs.