Start by putting in the chicken carcass in the middle of your slow cooker, it should be frozen. Cut the ginger, mushrooms and green onion into chunks, roughly chop the garlic and bruise the lemongrass to release the oil. Sprinkle on the peppercorns, five spice and salt over the top. Add in the vinegar and broth, use the additional water to fill the cooker all the way to the top of your slow cooker. Give it all a stir around the chicken bones.
Cook on low for 12 hours or more. When ready use a thin strainer or cheese cloth and drain off all the broth into a stock pot and discard all the flavor items.
Each person can customize their dish by adding slices of beef and submerge them all in the broth to cook right on sight to a medium/ medium rare. Top with a sprinkle of green onion, bean sprouts and basil. Use a squeeze or two of lime and fire away with the zippy sriracha and chili flakes to taste. For a sweet element, you can add a touch of hoisin or have it on the side to just dip the meat in. Have fun with it!