What exactly do I need for this recipe I have?

I am making siopao sometime this week (I'm addicted to them, but this is the first time I'll be making them myself), and I need some kind of pork that will be easily shred into little bits when it's done cooking, I'm a beginner, so do I buy a pork chop, roast, what? I really don't know! Please, be specific. Help! And thank you so much!
In case you don't know, siopao are these yummy little steamed Filipino pork buns, oh! They are just to die for, but expensive to buy at the Asian market, so I'm going to make a bunch here at home and freeze some for later.

I would suggest a pork shoulder, called Boston Butt. Season well with Filipino spices and let marinate for awhile, even overnight. Sear the pork in a hot pan with a touch of oil, turning on all sides. Transfer to a pan that will fit in the oven and add water just to barely cover the pork and maybe some citrus, like a few oranges or limes to really help break down the tough meat. Cover the pan with aluminum foil and bake at 250 degrees for like 4 or 5 hours or more depending on how big of a cut of meat you have. When you can insert a fork and pull down and the meat just falls off the bone you are getting close. Let the pork cool and rest for awhile, like 20 minutes. Remove from the liquid and the meat should shred into little bits and be ready for any kind of sauce. You can even add a really good BBQ sauce and enjoy on a little Hawaiian sweet roll. Hope this helps.

Pork Butt, is really the shoulder section of the pig and not the posterior. But, rather than roasting, this meat will become totally unctuous if braised. Braising is cooking it in liquid for an extended amount of time. It will be fall off the bone tender.

Here's my article on braising which is for veal shanks. Just substitute the pork shoulder and increase the fluid.

http://www.foodreference.com/html/artbra...

boneless pork shoulder

when you can twist a fork in it, it will be done and shred easily.
You can do it in a crock pot if you have one.

use ground pork...and if you want to know a recipe for asado siopao, here's the website:

Get Boston Pork Butt...its a roast

its is easiest to roast it in the oven slowly...you can cut down the time drastically by cutting the roast into 1 inch pieces...it will roast at 325 for about an hour and will be perfect for shredding