After days trying to figure out how to develop a MEAN app (Mongo, Express,Angular,Node) I have to admit that backend programming is unfortunately not my strong suit and I have to put my SteemBuddy App project on ice for now.
My apologies for setting expectations to have the app ready by end of this week, I did not expect that the last bit is such a hard hurdle for me to overcome. If I ever decide to try developing an app again, I will only write about it on steemit once it is done and ready to use.
Fortunately there is a way to lookup steemias on SteemData, using the free MongoDB manager Robomongo
To access the database, download Robomongo and login into the SteemData Server using the credentials shown on the SteemData website.
At this point a big thanks to 
who created SteemData!
Once you signed in to SteemData, go to Steemdata -> Collections -> Accounts
This shows you all the various documents that contain information about Steemit.com users.
In order to find people with a specific interest, copy the following line between the curly brackets {} like shown below.
'json_metadata.profile.about': {'$regex': "Cooking", '$options': "i"}}, projection={"name": 1, "_id": 0, "profile.location": 1, "rep": 1, "profile.about": 1, "profile.profile_image": 1
The the word after $regrex is the keyword for the search.
The text after projection restricts the shown fields to name, profile location and the text in the about field.
In this example all Steemit.com users who have the word cooking or Cooking in their about field are displayed. If you want to lookup users with another interest, simply replace the word "cooking" with some other word.
