Wash and peel the asparagus and cut off the woody ends. Wash lemon hot, grate dry and peel in thin strips with a zest ripper. Halve the lemon, cut off 4 thin slices.
Squeeze juice from the remaining lemon. Fold parchment paper to a bowl (approx. 20 x 25 cm). Season asparagus with salt, pepper and sugar. Spread lemon juice, peel and slices and butter in flakes on the asparagus.
Pour white wine evenly over the asparagus. Seal the package as tightly as possible. Cook in the preheated oven (electric cooker: 150 °C/ convection oven: 125 °C/ gas: level 1) for 45-60 minutes. Arrange asparagus and ham on plates.
Herb baguette tastes good with it.