Where do I mix these ingredients?

Hint 1 of 7:

You need a container that will also let you crush the flour.

Hint 2 of 7:

Think of something that a pharmacist might use.

Hint 3 of 7:

There is a stone mortar and stone pestle in the barrow back in the Region of
Earth.  Use the mortar as a container.

Hint 4 of 7:

Add the flour and fire water (see the previous hints if you don't know where
to get them), and then grind the ingredients with the pestle.

Hint 5 of 7:

Now you're ready to bake the mix.