12 large egg yolks, cleaned of all whites (200 grams)
1/4 teaspoon salt (2 grams)
4 cups ice cubes (475 grams)
2 cups water (475 grams)
1. Use sous vide device to heat water bath to 149 degrees F/65 degrees C. Alternatively, fill 8- to 12-quart cooler halfway with boiling water; close lid and set aside.
2. Using spatula or ladle, push yolks through fine-mesh strainer into medium bowl; gently whisk yolks and salt until just smooth (do not overwhisk). Pour mixture into 1-quart double-zipper zipper-lock bag; seal zipper, leaving ¼-inch opening on 1 end. Holding bag near opening, allow bag to lie flat on counter so that egg mixture fills bag and pushes air out opening. Seal bag fully.
3. If using cooler, add cold water until water in cooler registers 151 degrees F/66 degrees C. Gently lower bag into water bath or cooler, allowing any remaining air bubbles to rise to top of bag (do not let go of bag). Reopen 1 corner of zipper, release remaining air pocket, and seal bag fully. Release bag into water bath or cooler and cook for 32 minutes. If using cooler, stir in boiling water as necessary to maintain water temperature of 149 degrees F/65 degrees C; keep cooler lid closed when not adding water.
4. Meanwhile, combine ice and water in large bowl; set aside.
5. Remove bag from water bath or cooler and immediately transfer to ice bath; let chill until cold to touch, at least 10 minutes. Transfer sauce to airtight container or squeeze bottle and refrigerate until ready to use.