Color
Creamy white is what you’re looking for. Skip anything dull-colored or with spots.
Size
This actually doesn’t really matter when it comes to cauliflower -- size isn’t related to quality, so just pick whatever size you need.
Buds
Look for buds (aka all the white pieces that make up the cauliflower) that are close together and compact, not separated.
Leaves
The more thick green leaves surrounding your head of cauliflower, the better. These keep it fresh and protected. You don’t want any little flowers inside your cauliflower between the buds, though.
Storing It
Once you’ve picked out the perfect cauliflower, keep it in the fridge in a paper or plastic bag, with the stem side down (this keeps moisture from gathering in the clusters). It’ll stay good for up to a week.
-- Paula Kashtan
Dec 15, 2010