Bottarga di tonno is the very tasty dried and salted calf of the Yellowfin or Bluefin tuna. The delicate calf is actually 'waste' or rather a remnant of the tuna that one, salt, dries and smokes lightly. The process is exactly the same as the bone targa di muggine. There is a taste and price difference between both botargas. The calf of the hardener is a bit bitter and the price is a lot more expensive than the calf of the tuna. The bottarga di tonno is very tasty, especially if it comes from the Bluefin tuna. Yellowfin bone targa is thinner and less tasty. A good bone targa is dark red in color and in the middle lighter, against orange.