Preparing/Seasoning/Using a Carbon Steel Pot
You can't do it. Cooking vessels are divided into reactive and non-reactive. Practically all uncoated metal pots (except for stainless steel) are reactive. This means that they will leach an off taste into the food. There is no way around it, and seasoning won't help either. It is effective for frying, but not boiling. 

If you want to have no metal leached into your food, you need to buy a nonreactive pot.