1. Combine vinegar, water, sugar, salt, mustard seeds, and turmeric in a medium saucepan and bring to a simmer, stirring occasionally to dissolve sugar.
2. Let mixture cool to room temperature. Meanwhile, divide shallots and cauliflower between 2 quart-size jars. Pour cooled brine over cauliflower to cover.
3. Seal and refrigerate for at least 2 days before using and up to 1 month.
Source: Hannaford fresh Magazine, July - August, 2017