1. Melt the butter in a microwave or small saucepan, over a gentle heat.
2. Once the butter has melted, allow for it to separate, then poor into a container, discarding the milky solids.
3. Half fill a medium sized pan with water, and bring to a simmer.
4. Place the egg yolks in a metal brown pan, add the water, then place over the pan of water and whisk until the egg yolks had doubled in volume, being careful not to scramble the egg yolks.
5. Remove the pan from the heat and poor away the water, place a tea towel over the pan and place the metal bowl over the top. The towel will help steady the bowl while you are whisking in the butter.
6. Start to whisk the egg yolks again slowly adding the butter to avoid the mixture splitting. Once all the butter has been added season with Tabasco to taste and a little salt.
7. Cover with cling film and leave in a warm place.
8. Bring a medium sized pan of salted water to a gentile simmer. Crack your eggs into 4 ramekins and tip one at a time into the pan of water, making sure the water stays at a simmer to help set the eggs. Cook to your liking.
9. While you are waiting for the eggs to cook, toast your bagels.
10. Add caviar into the warm sauce. When the eggs and bagels are cooked, top the bagels with the smoked sturgeon, eggs and sauce.