curry base going green

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text from my brother! He is boiling up onions and garlic as a curry base and they have gone green. He wants to know why and I don't know but reckon once he adds the spices and/or curry paste, it will change colour again! Any opinions?

Green? Is there nothing in there other than the onions and garlic? Were they very young onions? that is odd.

I would advise him to add a teaspoon of turmeric and a good hefty squeeze of tomato puree to his curry paste/spices. That should sort it out.

thanks Greensleeves! Will text him now