a beautifully assonant phrase which can and should be used on any occasion where joy and elation are expressed.
the origin of 'awesome sauce' is probably from Strong Bad, although in that case he refers to a cleaning product with the trade name of Awesome Sauce. 'awesome sauce' has been adapted for use both as an exclamation or reserved sign of approval.
Being composed of something that is "awesome (awesomesauce), true(trufax), in need of more (desu and cowbell)" it is mainly used to describe something good that you want more of.
Wow! That ice cream was awesomesaucetrufaxdesucowbell!
adj: Take awesome, multiply it by the power of awesomesauce, then multiply it by the sheer awesome of a thousand ninjas, and you will have something that is pretty close to being awesomesaucetastic.
"Dude, did you see that guy? He just somersaulted off a 20 story building, fell 170 feet, snagged a kitten out of a tree, landed on his feet, stopped that guy from stealing candy from a baby, discovered the cure for cancer, and established world peace!"