My friend wants to go to a restaurant called Cafe Blossom and it's under the supervision of R' Andre Malik of Brooklyn (we've never heard of him before and this is the only restaurant that we know of that has his certification on it).

How is someone supposed to find out about the reliability of a specific mashgiach? OU won't comment (what else is new), so is there any other way to find out if a restaurant is acceptable according to Orthodox Kosher standards?

I would not trust a man named Andre. Especially not a Rabbi Andre.

Malek.
He has other establishments under his supervision.
http://www.kosher-ny.com/listings/searchh.php?hg=33

Don't know if any of them mean anything to you though.

There's a fool-proof method and a common method.
The fool-proof method might be a bit awkward (you've been warned!)
The common method is not very reliable.

Common method first: Do the customers at the restaurant look frum? How frum?
Fool-Proof method: Entrapment. Try to get the mashgiach to eat something treif. See how he reacts.

ETA: None of the places he supervises are fleishig, and most are vegetarian, for crying outloud. You could trust a monkey as a mashgiach for a vegetarian place.

I trust him over the Star-K.

What if the veggies aren't checked?

What veggies? Lettuce? Do you really think they'd look over every leaf? Cooked vegetables? You can rely on bitul...

And here I read it as 'how to find out if Moshiach is reliable'.

Broccoli, lettuce, etc. Are they checking at all? Is the food even kosher? Just because a restaurant has a name on the certificate doesn't mean that someone is actively checking to make sure that the restaurant is only using Kosher food. If a mashgiach isn't constantly on the premises, how do you know if anything is Kosher at all?