Combine veal, pork, onion, 3 cups water, and 1 teaspoon salt in a large saucepan. Bring to a boil. Reduce heat; cover and simmer 1 hour or until meat is very tender. Remove meat from broth; set aside to cool. Reserve broth in saucepan. Simmer until broth is reduced to 1 cup. Set broth aside.
Position knife blade in food processor bowl; add meat. Process 3 to 5 seconds. Scrape sides of bowl with a rubber spatula. Process 3 to 5 additional seconds or until meat is ground. Remove meat to a large mixing bowl. Set aside.
Soften gelatin in 1/2 cup water. Stir into broth. Bring to a boil; cook 1 to 2 minutes. Set aside.
Add mayonnaise, eggs, vinegar, mustard, sugar, 2 teaspoons salt, pepper, and broth mixture to ground meat in mixing bowl; stir well. Spoon into a lightly greased 8 1/2- x 4 1/2- x 3- inch loaf pan. Cover and chill overnight. Unmold onto a lettuce- lined serving plate. Garnish with parsley and carrot flowers.