How to Make It
Push the rose petals into a clean 12- to 16-ounce glass bottle, using a chopstick to pack them down if necessary. Set a funnel into the top of the bottle.
In a small nonreactive saucepan, warm the vinegar over moderate heat until hot to the touch. Pour the vinegar through the funnel into the bottle. Using a chopstick, push the petals down to disperse them in the vinegar. Allow the vinegar to cool to room temperature and then secure the lid or trim a cork to fit the top.
Let the vinegar sit in a cool dark spot until bright red and fragrant, about 1 week. Strain the vinegar to remove the petals.