What's a good substitute for cilantro?
This writeup suggests substitutes:
I've quoted the most promising option. It seems that Vietnamese Coriander is not really from the coriander family and closely mimics the flavor of cilantro.  Let me know if this works.


  Vietnamese coriander or Persicaria odorata is a
  herb, the leaves of which commonly
  feature in Southeast Asian cuisine,
  particularly in Vietnam and Malaysia.
  It is also known by the name of
  Vietnamese cilantro, Vietnamese mint
  and Cambodian mint. Though it is not
  related to mint, its flavor as well as
  appearance can be said to slightly
  resemble mint. It is more commonly
  included in salads and soups. The
  flavor of Vietnamese coriander closely
  mimics the flavor of cilantro, and
  hence, can be used as a cilantro
  substitute. This herb is believed to
  be very effective for some common
  gastrointestinal problems like,
  indigestion, stomachache and
  flatulence.