We've got our hands on a packet of Vegg - billed as a vegan egg yolk. The mix consists of little more than a blend of yeshi (nutritional yeast) and sodium alginate (an extract of brown algae) with a few vitamins, but is a versatile egg yolk replacer.
Sodium alginate is the stuff molecular chefs use to 'spherify' liquids, to make fruit juice 'caviars' and the like. The Vegg mix can be spherified into perfect round egg yolks...but not straight out of the packet - additional purchases are required for that.
Out of the packet you can make yourself a quiche, an omelette or French toast.
UPDATE: Read our full review of The Vegg vegan egg yolk
See also our French Toast made with The Vegg post.
See also our Vegg 'n' Bacon english muffin post
Here's one that didn't work - hard boiled Vegg yolk...we just re-invented gnocchi!