Set the Instant Pot to sauté and add oil to the insert. When hot, add lamb shoulder and brown on both sides, then remove, place on a plate and set aside. Turn off the Instant Pot, add stock and scrape the bottom of the insert to deglaze. Then mix in the anchovies and garlic purée.
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.
Add the lamb, garlic, salt and all the spices and saute for 5 more minutes until fragrant. Add the vinegar, tomato paste, honey, stock, chickpeas and raisins and stir until combined. Cover and set the Instant Pot (or pressure cooker) to pressure cook setting for 50 minutes on normal/high.
Rinse the lamb with cold water and pat dry with paper towel. Season with salt and pepper and using your hands rub seasoning all over the lamb to coat it well. Select SAUTE – High – 30 minutes and press START. When preheated, add 2 tbsp of oil to the inner pot, and sear the lamb on all sides for about 5 minutes per side.