For the hollandaise sauce:
- Melt butter with a bain-marie. In a large bowl, set egg yolks, a bit of lemon juice and 10 ml (2 teaspoons) of water. Progressively rise heat with continuously whisking. The mixture need to be foamy and unctuous. Remove bowl when temperature gets to 130 °F (60 °C). Then add, out of heat, butter like a mayonnaise (progressively). Season. Set at warm for 45 minutes at 100 °F (50 °C).
- At the center of a plate, set puff pastry and asparagus.
- Pour sauce and serve.