"He pushed up his visor and toasted them with a flagon of mead. 'Merry--hic--Christmas! Password?'" (Prisoner of Azkaban 230).
Like brewing beer, making mead takes several weeks. There are many different recipes available online, from the very simple to the extremely complicated. I've said before that mead is technically wine made from honey. I don't think I mentioned however, that based on the type of yeast (and how much yeast) is used in the recipe, it often tastes more like beer than wine (unless you infuse it with berries or other delicious things like a friend of mine just did... yummy).
Because it takes so very long to make, we will not be brewing mead here on In the Kitchen with Harry Potter. But if you're curious, I definitely recommend you google yourself a recipe and choose whichever one suits your fancy!