Once did some work for a food Technologist.
Her job was testing all stain removing treatments for manufacturers of foodstuffs, so that when customers rang complaining that they had a stain from their product they could tell them the most effective treatment.
The most effective treatment for curry stains is
DIRECT SUNLIGHT.
Not very good but better than anything else on the market.
Not very encouraging is it, Good Luck i think you'll need it.