- 2 medium onions, chopped
- 3 carrots, cut into 1/4-inch dice
- 2 celery ribs, cut into 1/4-inch dice
- 1/4 cup vegetable oil
- 3 (6- by 6-inch) matzos, broken into 1/2-inch pieces
- 2 tablespoons chopped fresh flat-leaf parsley leaves
- 1 large egg, lightly beaten
- 3/4 teaspoon salt
- 1/4 teaspoon black pepper
- 1 (3 1/2- to 4-lb) boneless veal breast (1 1/2 inches thick)
- 1 small onion, quartered
- 2 garlic cloves, smashed
- 1 tablespoon vegetable oil
- 2 teaspoons paprika (preferably sweet Hungarian)
- 1 1/2 teaspoons salt
- 1 teaspoon black pepper
- 2 fresh thyme sprigs
- 1 1/2 cups water
- Special equipment: a carpet, darning, or upholstery needle; kitchen string
- Cook onions, carrots, and celery in oil in a wide 3 1/2- to 5-quart heavy pot over moderate heat, stirring occasionally, until vegetables begin to brown, 8 to 10 minutes.
- While vegetables are cooking, put matzos in a colander and run under hot water until softened.
- Remove pot from heat and transfer half of vegetables to a bowl. Cool vegetables in bowl 5 minutes, then stir in matzos, parsley, egg, salt, and pepper.
- Preheat oven to 350°F.
- Trim as much excess fat as possible from veal. Cut a large pocket in veal breast: Beginning at center of thickest side, insert a large knife horizontally and cut into center of veal as evenly as possible, leaving a 1-inch border on 3 sides.
- Purée onion, garlic, oil, paprika, salt, and pepper in a food processor or blender. Put veal breast on a cutting board and rub inside of pocket with 2 tablespoons purée. Fill pocket loosely with matzo stuffing, leaving a 1-inch border on cut side. Sew pocket closed with carpet needle and kitchen string.
- Pat veal dry and rub both sides with remaining purée. Put thyme sprigs over vegetables remaining in pot, then top with veal. Add water and bring to a boil.
- Cover pot with lid and braise in middle of oven until meat is very tender, 3 to 3 1/2 hours. Transfer veal with a wide metal spatula to a clean cutting board and let stand, loosely covered with foil, 30 minutes.
- Discard thyme sprigs and skim any fat from sauce. Discard string, then cut veal across the grain into 1-inch-thick slices and serve with sauce.