What am I

Written by: Seren Roberts

I am so expensive
I am very hard to grow 
I am grown in Madagascar
 that is faraway I know
I am used in sweet and savoury
I am pure, spicy, delicate too
with a peculiar bouquet
Have I given enough clues?.

What am I?

My first is a commercial vehicle of the white kind
My second says that i am sick
My third is a portion of the French expression, OOH la la
My fourth is the name for the water found at the beach 
My fifth is the 4th letter of the alphabet

The answer is 

Vanilla Seed