The most important thing about asparagus is freshness: size doesn’t matter (don’t you believe it, boys!), but uniformity of thickness does. Look for a high proportion of green sprout over white woody stem. English asparagus is generally very good, but often the paper wrapper covers an unacceptable amount of white wood, so pull one stalk out of the bunch to check (thereby incurring your local market trader’s wrath). Very large asparagus are too expensive, but very thin ‘sprue grass’ can be delicious. Watch out for damaged, slightly wet, tips, and withered corrugated stems, as both of these indicate age.
All asparagus needs peeling, with the exception of sprue. The woody white bits need trimming, but keep all trimmings and peelings for making a stock base for asparagus risotto. Asparagus grows in sandy soil, and will always need a wash.