Use a dough like pizza.
Slice onion and put it in a pan with a teaspoon of vinegar, a little oil and a pinch of salt, after a few minutes add the asparagus.
When it is cooked, let cold it and put it in the spreaded dough.
Roll it and cook in heat oven for 15' at 230°
Finally, pour a drop of oil and a pinch of salt, cut into slices and serve.