Pyth, 32 31 bytes
Not a very optimal solution feelbecause I couldn't get the short function defintion using the L command. Feel free to help me out here
Code
DtZJrZ0R.ehSmadksmxdcJ1"aeiou"J
Big-Pyth Version
def
tail
zero-var
implicit-assign
auto-var
lower
zero-var
0
return
enumerate-map
head
sorted
map
absolute-difference
map-var
enumerate-map-ind
flatten-once
map
ind-all-occurrences
map-var
chop-into-size-n
auto-var
1
str-start aeiou str-end
auto-var