I recently bought a Vietnamese Coriander plant which although a rather
different species has a similar taste to 'conventional' coriander,
albeit IMO slightly more spicy.

It's a very attractive plant with elliptical leaves with a darker
section in the middle and is also a perennial. Since I bought it, it's
been sprouting away very happily and I've also been able to root a
cutting from it in a matter of days. As it's a tropical plant it will
need to be brought indoors over the winter.

Perhaps it would be a worthwhile alternative to normal coriander?