In a large casserole dish (or large ovenproof pan), heat oil and butter over high heat. Sear the veal cubes on all sides.
Add onion, garlic, mushrooms, carrots and celery stalks.
Pour in broth, wine, tomato paste and pearl onions.
Add salt and pepper to taste. Mix well.
Cover and cook in the oven for 2 hours.
Add tagliatelle and mix. Cover and continue cooking for 10 to 15 minutes or until the pasta is al dente. Pasta must be well covered with broth to cook.