In brief
In asparagus, preparation involves separating the harder lower end. The thickness of the stems also matters when cooking.
Useful to know
First, separate the woody lower end of the asparagus. The University of Iowa has proposed that one stem bends to its natural refraction, and that it serves as a guide for pruning the others. [1]
When buying, it looks for tight tips and stems without wilting. Rinse under running water before cooking. For short storage, the manual describes a refrigerator, a damp paper towel around the bottom edges, and an envelope. [1]
If there are very thin and significantly thicker stems in a relationship, it does not track only one total minute for the entire amount. Check the texture of the different sizes. The University Grill Guide itself specifies that the time depends on the thickness. [1]
For the first try, choose one method - roasting, grilling or stewing - and keep the other conditions relatively constant. This helps to understand the preferred texture without attributing any difference to the product itself.
Sources
For further detail and to check the information: