Will I never be able to cook anything needing tomatoes in a seasoned cast iron Kadhai? https://cooking.stackexchange.com/a/5863/6168


  If you put any acid in cast-iron, you are harming your seasoning, and leeching iron into your food. This will affect the taste of your sauces, I find pan sauces taste metallic when made in cast iron.


Indian dishes often require tomatoes in most of the dishes. I am not intending to cook any tomato sauces in the Kadhai. Will I never be able to cook any Indian dishes requiring tomatoes in a well seasoned iron Kadhai (assuming I'll re-season again)?
The PH scale ranges from 0 - 14 with the lower numbers being more acidic than the higher number. Canned tomatoes are generally around 3.5-4.5 on the acidic scale, in other words just above the half way point below neutral 7.

As long as your tomato based sauce is not left in your seasoned Kadai (as Kristina rightly points out) for a long timeframe and your kadhai is washed out immediately after use no damage to the seasoned coating should occur.

Just remember to wash out your Kadai (with warm water and a cloth) immediately after use to preserve the seasoned coating.