Turn the Instant Pot to the sauté setting and warm the oil. Brown the lamb meat in batches, being careful not to overcrowd the pan; you don’t want the meat to be touching while it sautés, otherwise, it will steam instead of sear. Add a sprinkling of kosher salt and some fresh ground pepper as it sautés.
Place all the meat and its juices, the garlic, pearl onions, broth, balsamic vinegar, tomato paste, paprika, and a little more salt and pepper in the pot. Select the stew/meat setting and set to 30 minutes, making sure the vent is sealed. Once it’s finished cooking, carefully release the steam using a dish towel to cover the vent and tongs to open the valve so as to prevent a steam burn.
Open the Instant Pot, add the remaining vegetables and give everything a stir. Close the lid and seal the valve and set to manual/high pressure, for 5 minutes. After the vegetables cook, carefully release the steam using a towel and tongs again.
If the stew seems too thin, remove a cup of cooking liquid from the pot and whisk in the arrowroot flour. Add the mixture back to the pan and stir. Set the stew to the sauté setting, uncovered, for 10 minutes and stir, until the stew is thickened. Taste for seasoning and serve.