First off, put the Instant Pot onto "Saute" mode and then move it to "More."
Add in your oil and then pat dry the lamb shanks.
Season the shanks with the pepper and salt. After the Instant Pot gets hot enough, add in the lamb shanks.
Cook the shanks about 4 minutes per side until they are brown.
Remove the lamb shanks and then put them onto a plate.
Add the garlic into the Instant Pot, and then stir for about 15 seconds. Add in the wine next, and then cook this for about 2 minutes.
Add in the basil, tomatoes, and oregano. Cook this together for about 2 minutes.
Put the lamb shanks back into the Instant Pot, and then put the lid on the pot and seal the valve.
Cook on "Manual" high pressure for about 45 minutes. Once done, allow for a natural release of pressure for about 15 minutes.
You then can release the remaining pressure quickly, and then get out your lamb shanks. Add a little of the sauce on top and serve.
You can add the parsley at the end for an optional garnish.