Chicken: whatever you desire, legs, breast, etc; typically I use either one package of boneless thighs which is usually 6 - 8 or split it up...3 - 4 legs plus 2 breasts.
1 white onion; med to large size
8-10 of cloves of garlic; this is preference, sometimes I use an entire head of garlic
Ginger root; a good chunk (2-3" piece), outer skin removed, sliced
2-3 Habanero peppers
1 bunch of fresh spinach. try to get the kind with stems and not just leaves
1/2 cup of fish sauce
salt and pepper
Optional: Package of large mushrooms, cut into large chunks
Optional: Cooked rice (rice is not cooked in the soup, the soup can be poured over the rice before serving.)
Chop the garlic, slice the ginger, and cut up the onion (sliced, or halved and quartered, up to you). Cut the chicken into large-ish bite-sized pieces. Rinse the spinach. Clean and cut the mushrooms. Habaneros can be included whole (for a less spicy soup), or you can remove the stems/seeds and slice (more spicy). Extra spicy...include the seeds :) Set all ingredients aside.
On medium heat, drop about a tablespoon and a half of oil into a pot (at least 4 quarts, and one that you can cover). warm it up and dump the garlic in. Sauté for a min or so, dump in onions and ginger. Sauté for a few mins. (watch that heat isn't too high or you'll burn your mixture).
Dump in chicken parts (heat should still be at med). Add salt and pepper (just a few shakes of salt; more pepper than salt). Cover and let sit for a couple of minutes. Open up, mix around, cover. Repeat this 3 times or so and then lower heat to low-medium. Continue doing this until 20-25 mins are up. Sooner or later, you'll see the chicken is now being cooked in a bit of juice generated by all of the steam.
After 25 mins are up, add cold water to pot, enough to barely cover the chicken. At this point, add the fish sauce. I'd guess about half a cup. Add the habaneros too, just let them swim. cover and raise heat again to med. after you reach a boil, open and stir around and cover. Lower heat to low med. Repeat the open, stir, cover process until 20 mins has passed. After the last cycle, take your spinach and place it on top of the everything in the pot and cover. (If you include mushrooms, add them about 5 min before the spinach). Keep heat at low med for another 5 min and then turn the heat off...you're all done.
Note: if you prefer the soup to be less spicy, you can remove the habanero peppers at this point, or earlier, as desired.
I usually serve in a large bowl, over rice.