Preheat oven to 300 degrees F (150 degrees C).
In a large dutch oven or heavy pot, heat Olive Oil (2 tablespoon) over medium high heat. Add the Lamb Shank (4) in two batches, and sear on all sides until browned, turning with a pair of tongs, 7-9 minutes each. Transfer lamb to a tray.
Add Olive Oil (2 tablespoon) to a pot, and stir in the Carrot (4) and Celery (4 stalk). Cook until slightly softened, 5 minutes.
Add Cremini Mushroom (16 ounce) and Shallot (4) and cook 4-5 minutes, until tender. Stir in Red Wine (1 cup), Tomato Paste (4 tablespoon), and Low-Sodium Beef Broth (2 cup).
Add Fresh Thyme (4 sprig), Garlic (4 clove), and Bay Leaf (2). Transfer the lamb shanks back to pot, nestling them into the mixture. Cover tightly with lid, and place pot in oven. Braise 2 1/2 hours, or until fork tender. Season with Salt (to taste) and Ground Black Pepper (to taste).
To cook in a crock pot, brown lamb shanks as noted previously. Add the carrots and celery mix. Stir to combine, then nestle lamb shanks into vegetables and broth. Refrigerate until ready to cook.
Place slow-cooker vessel into the crock pot cooker. Cover with lid, and set slow cooker to low. Cook for 6-8 hours. Serve and enjoy!