Place tongues in a pot just large to hold them both and cover with water. Cover pot and bring to a boil. Lower heat and simmer 1 1/2 hours. Remove from heat and allow to cool.
Peel tongues and remove fatty parts from lower portion of muscle. Slice tongues into 1/2-inch pieces and set aside.
In a heavy bottom Dutch oven, heat olive oil over medium heat. Add onions, celery and carrots and cook, stirring regularly until lightly browned, about 8 to 10 minutes. Add orange juice, vinegar, chicken stock and tomato sauce and bring to boil. Add tongue pieces and cook uncovered at a very low boil until liquid has reduced by two-thirds, about 30 minutes. Serve with torzelli (separate recipe) and sprinkle with grated orange zest.
Saute the onion and garlic in the olive oil over medium heat until translucent, but not brown (about 10 minutes). Add the thyme and carrot and cook 5 minutes more. Add the tomatoes. Bring to a boil, lower the heat to just bubbling, stirring occasionally for 30 minutes. Season with salt to taste. Serve immediately, or set aside for further use. The sauce may be refrigerated for up to one week or frozen for up to 6 months.
Recipe Courtesy of Mario Batali