Combine ground meats in a large mixing bowl then add bread crumbs, onions, water, eggs, 1 Tbsp salt and 1 tsp pepper.
Mix until all ingredients are very well combined )your hands work well for this); then vigorously knead mixture for 3-5 minutes.
Spread the veal skin-side down flat on work surface; using a small, sharp knife, make small cuts in the thickest areas of the meat to make it lie even flatter. Cover with plastic wrap or a towel.
With the side of a cleaver or meat mallet, pound meat to a fairly uniform thickness.
Remove cover and sprinkle veal liberally with salt and pepper.
Spread 1/2 the stuffing on the veal, leaving a 2" border of veal exposed all around the sides.
Lay hard-boiled eggs in a row down the length of stuffing & spread remaining stuffing in a layer over them.
Bring one long side of the veal over the filling to the middle and tuck-in the two ends. Bring the other side over the filling to enclose it very well.Tie up with string. tie rolled veal crosswise at 2" intervals, then with more cord tie it lengthwise.
Place the rolled veal seam-side down in a shallow roasting pan large enough to hold it.
Pour in 1 1/2 cup chicken stock and roast for 2 hours basting occasionally with the pan juices.
When meat is golden brown carefully transfer it to a serving platter; remove & discard cords.
Bring juices remaining in pan to a boil over high-heat. If most of liquid has cooked away add remaining 1/2 cup chicken broth to pan.
Scrape into it any bits that may be sticking to bottom and sides of pan. Remove from heat then stir 1/2 cup sour cream into sauce 1 Tbsp at a time. Season to taste.
Slice veal roll crosswise into 1" rounds and arrange slightly overlapping down center of a large preheated platter. Moisten them with a few Tbsp sauce and serve remaining sauce separately.