I am writing this a few weeks after making the dish, going strictly from memory:
2 cans condensed Chicken Soup
2 cans Water
2 inches of sliced Ginger Root
3 pieces dried Galanga
2 stalks Lemon Grass
1 bunch Green Onion
The most interesting part in all this was that instead of slicing the Lemon Grass thin (in ¼ inch slices, as per normal), I cut the stalks into 6" pieces; and then, unwrapped the leafs. I have no idea why folks slice the stuff into thin disks. It unwrapped beautifully, providing me with individual leaf sections six inches long.
After boiling the lot off-and-on for a few hours, I added:
1 can Coconut Milk
1 can Water
3 teaspoons Soy Sauce
2 teaspoons Fish Sauce
3 Lemons, juiced
If there is a 'secret' ingredient to this dish, it is the Lemon Juice. It pushes both the heat and the flavour to the back of the mouth: fills it out, if you will.
Also, I determine Coconut Milk quality by calories, assuming that the can with the most calories has the highest concentration of the good stuff. It varies wildly.
Finally, if cooking for myself, this is when I would have added Red Pepper (maybe a teaspoon, or so) or some Chili Paste (the stuff packs a punch).
About 45 minutes prior to serving, I brought the lot to boil, adding:
10 Chicken Thighs
I omitted any Mushrooms.
And provided a small dish of chopped Cilantro, as a garnish.
It tasted quite good.
But for myself, I would forgo the added water. It just thins the flavour. On the other hand, some folks like the flavour a bit thin and that's why it was added this time around.