Season the veal T-bones with salt and pepper. Over medium-high heat, heat 2 Tbs. of the butter in a wide, heavy skillet until it bubbles. Brown the T-bones on both sides. (You don't want to cook them all the way through at this point.)
Remove the veal from the skillet. Add 1 1/2 cups of the wine to the skillet, along with the onion, parsley stems, and peppercorns. Bring to a boil and lower to a simmer. Whisk the pan contents to dissolve the browned bits sticking to the pan. Allow to continue simmering.
Cut the bones out of the T-bones and add the bones to the pan. Slice the lean of the veal into pieces about three-quarters of an inch thick and an inch or two long. Place the veal on a plate, cover, and keep warm.
After the stock in the pan has simmered about ten minutes, remove the bones and strain the stock into a bowl. Rinse the pan.
Over medium heat, add the remaining butter and bring to a bubble. Add the mushrooms and leeks, and cook for about five minutes, or until the leeks are soft.
Add the remaining wine and bring to a boil. Hold it there for about two minutes, then add up to a cup of the strained stock, the cream, mustard, tarragon, and chervil. Whisk to blend thoroughly. Add the sliced veal along with all the juices that have collected in the plate. Lower the heat to the lowest possible setting, and cook for 30 minutes, uncovered.
Remove the veal to serving plates. Add the sliced dill pickle to the sauce and heat through. Adjust seasonings with salt and pepper. Return the veal to the sauce to coat. Spoon the sauce over the veal and served with rice on the side.