In a large bowl, combine Marinade Mixture ingredients. Add lamb shanks and coat well. Set aside and allow to marinate for at least 30 minutes.
Once 30 minutes have elapsed, add 1/4 cup olive oil to the Instant Pot. Using the display panel select the SAUTÉ function.
When oil gets hot, brown the meat on all sides, 3-4 minutes per side. Meat will not be cooked through. Do not crowd the pot--you may have to work in batches. Transfer browned meat to a shallow dish and cover loosely with foil.
Add onion, carrots, bay leaves and remaining marinade to the pot and Sauté until onions are soft, 4-5 minutes.
Add wine to the pot and deglaze by using a wooden spoon to scrape the brown bits from the bottom of the pot, then simmer and reduce by half (about 10 minutes).
Add warmed broth and return the meat to the pot, turning once to coat.
Turn the pot off by selecting CANCEL , then secure the lid, making sure the vent is closed.
Using the display panel select the MANUAL or PRESSURE COOK function*. Use the +/- keys and program the Instant Pot for 30 minutes.
When the time is up, let the pressure naturally release (about 15-20 minutes).
Carefully remove the meat from the pot and cover loosely with foil, reserving juices.
Strain liquid and return to pot, discarding solids. In a small bowl, mix together cornstarch and cold water. Stir into the pot until thickened, returning to SAUTÉ mode as needed.
Serve lamb topped with gravy alongside mashed white or sweet potatoes, noodles or rice. Garnish with chopped parsley.