For those of you thinking about dark grey tile because it will "mask" dirt, be warned. This tile shows every coffee dribble, dirty shoe mark, sauce drop, etc. It is particularly dirty in this case because of all the outdoor yard work; with no sod in the backyard dirt was making its way through the backyard...
I started to clean with a grout brush and my "magic solution". Soon my sink looked like this:
And Ta da! Here is the after...
Fill a bucket (or sink) with 2 inches of water
Add 1 cup vinegar
Add a tablespoon of dishsoap.
Use a grout scrub brush for best results (I got mine at home depot). What I like best about this recipe is that it does not leave a film like baking soda recipes do.