Upvote:4
The question rests on a false assumption - that "country" can be tied to "ethnicity". There are a few countries that make an effort at racial purity, but I think that the concept has fallen by the wayside.
There is a second flaw in the question. "Democratically elected" means "elected by those we choose to have the franchise" - Generally this excludes women, minorities, and aboriginal inhabitants. If I recall correctly, nearly every election held in South Carolina until 1866 disenfranchised the majority of the population, so every elected official in South Carolina during that period would fit your definition. As would every elected official in Rome (which is why I cite Nerva below)
The third flaw is that the knee jerk response to some of the examples below is to deny that they don't represent distinct ethnic groups. D'israeli is a good example - I don't recall that he ever referred to himself as Jewish, but his contemporaries identified him as Jewish.
Upvote:5
I don't know if you meant complete democratic examples, but Alberto Fujimori is a pretty famous example of your request, he lead Peru a little longer than ten years, as he has been elected enacted neo-liberal reforms, then after a crisis his system turned into a nightmare.
In US, Obama could be an example if the US itself wouldn't be heterogenous already.