Preparation:

Trim any excess fat from the lamb shanks, if desired.

Season each shank generously with salt and pepper.

Browning the Lamb:

In your pressure cooker, heat the olive oil over medium to high heat.

Once the oil is shimmering, add the lamb shanks.

Brown the shanks on all sides, ensuring they get a nice, golden color.

Garlic:

After the shanks are browned, add the smashed garlic cloves to the pressure cooker.

Sauté them until they are lightly browned, ensuring they dont burn.

Adding Sauce Ingredients:

Pour in the chicken stock and red wine.

Add the tomato paste and rosemary, stirring well to ensure the tomato paste dissolves smoothly into the liquid.

Pressure Cooking:

Close the pressure cooker lid securely and set it to bring the pot up to full pressure.

Once the desired pressure is achieved, reduce the heat to maintain pressure and cook for 30 minutes.

Releasing Pressure:

After the 30 minutes, turn off the heat and allow the pressure to release naturally.

This might take an additional 10-15 minutes.

Preparing the Sauce:

Once the pressure is fully released, safely open the lid.

Carefully remove the lamb shanks and transfer them to a serving dish, covering them with foil to keep them warm.

Return the pressure cooker to the stove, set to medium-high heat.

Boil the sauce for about 5 minutes, allowing it to reduce and thicken.

If youre short on time or prefer a thicker sauce, you can whisk in some cornstarch slurry (1-2 teaspoons of cornstarch mixed with 1-2 teaspoons of cold water) to help it thicken faster.

Finishing Touches:

Once the sauce reaches your desired consistency, whisk in the butter until fully incorporated.

Then, stir in the balsamic vinegar, adjusting the quantity to your taste.

Serving:

Plate the lamb shanks and pour some of the sauce over each.

Serve with the remaining sauce on the side, so diners can add more if desired. Enjoy!