Serves 6.

3 tbsp. unsalted butter
1 lg. onion, finely chopped
3 slices white bread, crusts removed
1/3 c. milk
1 3/4 lbs. ground lean beef rounds
2 lg. eggs, lightly beaten
1/4 c. ice water
2 tbsp. sour cream
Salt and freshly ground black pepper, to taste
4 hard-cooked eggs, finely chopped
1/2 c. finely chopped scallions (green onions), greens only
4 tbsp. (1/2 stick) unsalted butter, melted
2 tbsp. mayonnaise
1/3 c. unflavored fine, dry bread crumbs, or more as needed
1 tsp. sweet Hungarian paprika
1/2 tsp. hot Hungarian paprika

Melt the butter in a small skillet over medium heat. Add the onion and saute until lightly colored, about 12 minutes. Meanwhile, soak the bread in the milk for 10 minutes. Squeeze the bread to remove any excess milk and crumble into a large bowl. Discard the milk.

Add the beef to the bread along with the onions and their cooking fat, eggs, ice water, sour cream, and salt and pepper. Knead until thoroughly blended. Set the meat loaf mixture aside. In a second bowl, combine the hard-cooked eggs, scallions and melted butter. Season lightly with salt and pepper and mix. Preheat the oven to 375 degrees. Line a baking sheet with aluminum foil. Spread the stuffing over the meat mixture, leaving a 1 inch border on all sides. Roll up like a jelly roll, starting on 1 long side. Peel back the waxed paper as you roll.

Place the roll, seam side down, on the prepared baking sheet. Spread with mayonnaise, using a rubber spatula, and sprinkle generously with bread crumbs and with sweet and hot paprika. Bake 1 hour. Cut into thick slices and serve.