Recipespeak is a funny kind of syntax peculiar to recipes:

• missing articles (a, an, the)
  "Put [the] lentils in [a] pot"

• missing direct objects (usually pronouns)
  "Cover [it, them] with water"
  "Set [it, them, the bowl] aside"
  "Drain [it, them]"

• missing subject and auxiliary verb
  "While [the pot is] boiling"
  "When [the toast has] browned"

• passive transfer
  "if desired [= if you desire]"
  "if wanted [= if you want]"

• fear of the object complement
  "finely chopped [= chopped fine]"
  "chopped finely [= chopped fine]"

Recipes-speak probably originated in the desire to save space
(especially in newspapers) and has long outlived its usefulness.

[mb is much more tolerant of recipespeak than m-c.]