Make the dressing by combining all the dressing ingredients except for the milk and stirring with a fork until well combined (some chunks of blue cheese are good – it shouldn’t be totally smooth). Thin it with just enough milk that it is still thick but pourable.
Slice the tomatoes into 1/4 inch slices, and lay in a single layer on a platter. Pour a puddle of dressing on top, sprinkle some blue cheese on top, scatter on the chives and serve.