1. Sauté the asparagus in butter in a frying pan.
2. Flavour with thyme and add salt and pepper.
3. Roll out the puff pastry and lay the slices of lard on the surface.
4. Place the asparagus in the centre of the pastry and roll the sheet over itself.
5. Cut into lengths of around 3 cm.
6. Brush the pastry with a mixture of egg yolk and milk.
7. Bake at 190° C for 12-15 min.