Fill a deep container with water. Using your immersion circulator, heat the water to 190 F.
While the water warms, fill a pint-sized jar with whole, peeled garlic cloves. Sprinkle them with sea salt and add a sprig of rosemary. Cover with extra virgin olive oil, allowing 1/2-inch of head space. Seal the jar tightly.
Place the jar in the water bath, and allow it to cook sous vide at least 4 and up to 6 hours. Use immediately, or transfer to the fridge and consume within about 2 weeks.
Try different herbs. If you don't have rosemary, try thyme, marjoram or oregano - or leave it out, too.