Boos Block Mystery Oil, 16 oz (MYSB). Official page lists all-natural food-safe ingredients and a food-grade oil that soaks into the grain. NSF certified. Official uses: butcher blocks, cutting boards, wood countertops, and wooden culinary utensils. Apply an even coat, let it sit overnight, wipe the extra. Specs from John Boos' Mystery Oil page (16 oz).
The 16 oz bottle. First step on a dry Boos board; cream goes on after.