Heat oven to 325ºF. Roast marrow bones 10 minutes. Scoop and set aside marrow in a hotel pan; discard bones.

In a large saucepan over medium flame, heat oil and add celeriac and onion. Season with salt and pepper. Sauté until cooked through but still toothsome. Remove from pan with a slotted spoon and set cooked celeriac and onion in pan with marrow.

Season veal shanks aggressively with salt and pepper. Sear on all sides and transfer to a hotel pan.

To the pan, add wine, tomato paste, rosemary, thyme, star anise, veal jus, and reserved vegetable scraps. Add enough water to cover shanks halfway and cook in oven 40 minutes, basting and adding water as necessary.

Flip shanks, cover, and braise 1 hour, until meat is tender. Coarsely chop meat and place in pan with marrow and sautéed vegetables; combine. Cover with plastic wrap and refrigerate overnight.

Through a chinois, strain braising liquid into a storage container and refrigerate; discard solids.

Form veal mixture into Croquettes, moistening mixture with braising liquid as needed. Set up a three-part breading station with flour, eggs, and breadcrumbs. Double coat croquettes.

In a Vitamix blender, blend yolks and capers 10 seconds. With blending, stream in oil followed by lemon juice, parsley, and colatura. When combined, add tuna and purée. If sauce breaks, re-emulsify with stock.

In a deep fryer, heat oil to 330ºF. Fry Croquettes until golden and crisp. On a serving plate, arrange croquettes. Top with a spoonful of Tonnato Sauce. Garnish with caper leaves and bonito.