1. If using fresh asparagus, trim the stalks and cook in a pan of boiling water for 8 minutes. Drain and rinse with cold water.
2. If using canned asparagus, drain.
3. To make the Hollandaise sauce, whip the egg yolks in a food processor until frothy.
4. Melt the butter. When very hot, gradually add to the yolks, in a thin stream, with the processor on all the time.
5. Transfer to a bowl and chill the mixture until thickened.
6. Flavour the Hollandaise with lemon juice to taste and stir in the mint.
7. Use a serrated or electric knife to cut the bread into 25 thin slices. Cut away the crusts.
8. Spread bread slices with the Hollandaise sauce and place one asparagus spear, cut in half, on each piece.
9. Join two corners of each with a wooden toothpick.
10. Dot with more sauce. Place under a preheated grill/broiler and cook until crispy.