How to Make It
Bring a large saucepan filled with water to a boil. Add cauliflower and onions; cook 2 minutes. Drain; plunge into an ice-water bath. Drain. Remove onion peels.
Add 3/4 cup water, vinegar, and next 5 ingredients (through pepper) to pan; bring to a boil. Combine remaining 1/4 cup water and flour in a small bowl, stirring with a whisk. Add flour mixture to vinegar mixture; cook 1 minute or until slightly thickened. Remove pan from heat. Stir in onion mixture and cucumbers. Cool to room temperature. Place in an airtight container; cover and refrigerate up to 1 week.