Well done, Jib San! ^
Problem identified.
Since usagihouse isn't Japanese and shows excellent competency in English and was directing information at someone who probably doesn't speak Japanese this hadn't occurred to me.
And yes, there is PLENTY of misinformation about Prof Ikeda's umami.
The concept is currently being championed in the UK by Heston Blumenthal and was discussed here: http://www.flyertalk.com/forum/briti...s-wt-cw-9.html
In post 134 comes the idea that if umami was a pure fifth taste then umami taste receptors would pick it up like salt - Umami being no more than a fancy word for MSG. There's much more later with the conclusion that there's no point in bringing together umami rich foods as the addition of MSG (presumably as crystals) would do the job adequately.

In conversation I come across many more examples which show me that people don't understand or 'get it'.

I'm still not sure why raw egg yolk (as has been explained, there's none in egg white no matter which kind of 'umami' you're using) was chosen as an example for the OP as it is so rare to be offered egg without dashi or soy sauce seasoning. The deliciousness AND umami naturally present in the egg/egg yolk will be raised to glorious heights by the more discernable and complex deliciousness and umami components of the dried/fermented foods.

Perhaps the most spectacular way to experience umami naturally present in food is to seek out the highest quality gyokuro tea possible (you could go to a specialist tea vendor somewhere like a department store and ask for a recommendation for where to go to have it made for you). You can actually see the crystals where the umami is present in the dried tea leaves (just as you can if you peer into parmesan cheese). The taste is very different from macha (the powdered tea used in the tea ceremony or the green tea lattes) or sencha and you drink it in small cups at a low temperature. Gyokuro has a milky tinge and is absolutely exquisite. Since tea has so little taste of its own (mostly fragrance) the umami flavour really shines through - much more enjoyable than experiencing umami through kombu steeped water!

One of my favourite restaurants in Tokyo was Chez Tomo (disclaimer: I've not been back since they got the Michelin gong). My main reason for liking it was because they sourced organic vegetables from small, highly specialised producers and let those ingredients sing for themselves WITHOUT adding as many of the ubiquitous umami rich seasonings, broths and condiments that are included elsewhere. It was one of the few restaurants in the capital where you could eat excellent vegetarian and vegan dishes.
http://www.chez-tomo.com/ginza/index.html
I really have to stress how unusual this was/is (I've not been back for couple of years and it's easy to lose touch).
I'm actually very interested in the organic farming movement in Japan and can highly recommend "The One-Straw Revolution" by Masanobu Fukuoka. Akinori Kimura is also a huge inspiration to many Japanese farmers.