2 tablespoons olive oil
2 pounds beef shank
salt and ground black pepper to taste
1 onion, cut into 1/2-inch cubes
2 stalks celery, cut into 1/2-inch cubes
1 cup Marsala wine
1 (14 ounce) can beef broth
water to cover
2 tablespoons dried tarragon
1. Preheat oven to 300 degrees F (150 degrees C).
2. Heat an oven-proof deep skillet with a lid over medium-high heat on the stove; add olive oil. Season beef shank with salt and pepper. Cook beef shank in the hot oil until browned on all sides, 5 to 10 minutes. Transfer beef shank to a plate.
3. Saute onion and celery in the same skillet until onion starts to get translucent, 5 to 10 minutes. Pour wine over onion mixture and bring to a boil while scraping the browned bits of food off of the bottom of the pan with a wooden spoon.
4. Return beef shank to onion-wine mixture; add beef broth and pour in enough water to cover 1/2 to 3/4 the beef shank. Sprinkle tarragon over shank; cover skillet with lid.
5. Bake in the preheated oven until meat is falling off the bone, at least 5 hours. Season with salt and pepper before serving.