Begin this recipe by thinly slicing the liver into approximately 1/4 thick pieces.  Don't worry if your pieces aren't uniformly sized as liver is not the most uniform ingredient to work with.  Just remember that the thinner you can get the slices the more crunchy they will be so please experiment with what best suits your preference.  After slicing, dry off the slices using paper towels and sprinkle with salt.

Next begin prepping the rest of the ingredients starting with finely dicing the red onion and placing into a small dish.  Follow this with halving the avocados and slicing them (I went with a length-wise partition for aesthetics but normally I use this technique [1] because its quick).  Next quarter the limes followed with a quick rough chop of the cilantro.

Heat butter (or cooking oil) in a pan over medium-high heat.  I prefer using a cast-iron for this but other types will also work.  Make sure to turn on your range hood fan if you have one as frying liver can smell up your kitchen real quick.  When butter/oil is heated through drop your liver slices into the pan and cook for about 3-4 minutes per side.  Its difficult to do an exact flip on small pieces like this so I'll generally just watch and turn the pieces all at once until both sides are well seared.

Place the cooked liver in the middle of the plate surrounding by avocado and limes.  Sprinkle over the top chopped cilantro and red chili pepper flakes.

[1] http://www.realsimple.com/food-recipes/cooking-tips-techniques/preparation/slice-dice-avocado