Combine all sauce ingredients except bread crumbs. Puree in batches in a food processor.
In a large saucepan, cook the mixture for 30 minutes. Add bread crumbs, stir in well, and cook five minutes more. You now have a good bit of completed Rockefeller sauce.
Cook three steaks at a time. Brush the tuna with olive oil. Heat a skillet and cook the tuna about a minute and a half on one side. Turn the tuna and spread the Rockefeller sauce on top, about the thickness of three stacked quarters.
Put the whole skillet into a preheated 350-degree oven for five minutes.
Meanwhile, in a separate skillet heat the butter to bubbling and add the oysters. Cook until the edges curl, then add the Herbsaint. Careful! Herbsaint is inflammable! Flame it very carefully (do you know where the fire extinguisher is?), but it's not necessary. If you don't, let it bubble for about a minute to get rid of most of the alcohol.
Place the tuna sauce side down onto the serving plate. Place the oysters atop the tuna, and nap the whole thing with hollandaise. Put the plates into the oven on the top rack, and turn the oven to broil at 450 degrees. Glaze the hollandaise for about a minute, then serve. (Tell people that the plates are hot!)