Melt 30 g butter in a roasting pan big enough for both pieces of meat to fit next to each other. Flour both pieces and brown from both sides on medium heat. Add chopped onions, carrots, celery, half the garlic, marjoram, lemon zest, and season with salt and pepper. When the vegetables are lightly browned, deglaze with wine and simmer on medium heat until thickened. Add tomatoes and veal broth. Cover, lower temperature, and cook for 1 1/2 hours. Add more stock as needed to prevent sauce from being too thick.

When the meat is almost ready, add the remaining garlic, lemon zest, and the remaining butter. Stir and let simmer for a few minutes on medium heat for a fully developed flavor. Serve pieces of Osso Buco on a preheated round plate, add sauce, and serve immediately.