Greg B assured us:


In US English, the kitchen term 'sink' may refer either to
the basin or to the surrounding counter surface, particularly if the
latter is covered in ceramic tile, although 'kitchen sink' rather
consistently refers to the basin.

That's strange. In my seventy-six years in the US, I've never heard "sink" used to indicate the kitchen working surface, regardless of the material from which it's made.   Someone working on the counter beside the sink might describe himself as "at the sink" because of the propinquity to the basin, however.

Dave Oesterreich