Step 1

Heat vinegar, sugar, salt, and mustard seeds to a simmer in a small, non-reactive* pot over moderate heat, stirring only until sugar and salt dissolve. Remove from heat and stir in cold water, which brings down the mixture's temperature. Let cool to lukewarm.

Step 2

Divide vegetables between 3 or 4-pint jars (or two-quart jars). Pour cooled vinegar mixture over the vegetables and refrigerate until needed. Slaw will be lightly pickled within 1 hour and fully pickled within 1 day.