1.Fill and preheat the SousVide Supreme water bath to 153F/67C.
2. Zest the oranges, being careful to use only the orange surface of the peel, and not the white inner layer.
3. In a large (gallon 3.8 liter) zip-closure cooking pouch, combine the zest with the rosemary and vinegar, use displacement method to evacuate the air, and zip the pouch closed.
4. Submerge in the water oven and cook for 2 to 3 hours.
5. Strain the vinegar through cheesecloth or a fine mesh strainer, pour into a clean bottle, and seal.
Recipe courtesy of SousVide Supreme