A few words about this item from chef José Andrés:

Ventresca is a true prize: the tender, tasty mid-section of the tuna, fished during the peak of the season in northern Spain. Following a secret, handmade process perfected over five generations, this delicacy is cut and prepared fresh, then packed in olive oil to preserve its incredible flavor and nutritional benefits. With a fine glass of Cava, it's a treat your guests won't soon forget. Serve with a silver spoon!