To make serpent stew in Valheim, you will need one cooked serpent meat, one red mushroom, and two honey. You can make it inside a cauldron when you have all the required resources for serpent stew - you may need to upgrade it.
That said, You can get the cooked serpent meat you need by killing sea serpents that you can find in remote parts of the ocean biome.
See our how to kill sea serpents guide for more help on that front, tips for where and how to kill sea serpents in Valheim. Once you get the sea serpent meat, you'll want to take it to an Iron Cooking station and let it cook with a fire underneath it.
After a while, you will get cooked serpent meat - make sure to watch, or it will burn. After you pick up cooked serpent meat, you will also unlock the recipe for serpent stew.
To get both the mushrooms and two honey you need for the sea serpent recipe, you will need to search either the meadows or black forest biome for the mushrooms and make a beehive for the honey. If you need any help getting a beehive, we have a guide on that link above.
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