Set the Instant Pot on SAUTE and set it on NORMAL. Add 2 tablespoons olive oil.
When the oil becomes moderately hot add the diced sausages and saute until nicely browned. Do not strain the sausage fat.
Now, add the chopped onion and garlic and saute for just 1 min. They will slowly release a lovely aroma.
Add the shrimp stock and de-glaze the pot very well with the help of your spatula so that there are absolutely no bits and crumbs stuck at the bottom of the steel pot. This step is very important to prevent the BURN error. Do not tush this step.
Rinse the rice very well under running tap water several times until clear water runs through. This is very important.
Add the rinsed rice to the pot and give a good mix gently with the help of your spatula. Layer the rice in one single layer evenly by gently pressing down with the back of a ladle or spatula. Sprinkle 2-3 pinches saffron.
Now, layer the shrimps in a single layer on top of the rice. DO NOT mix or stir. CANCEL the SAUTE function.
Now, PRESSURE COOK on HIGH PRESSURE for 4 mins.
When the pressure cooking cycle is over the Instant Pot will begin to beep. Wait for NATURAL PRESSURE RELEASE (NPR) for 10 mins and than release the rest of the pressure manually by moving the valve from the SEALING to the VENTING position. Open the lid carefully. Turn off the Instant Pot.
Remove the shrimps and add the green peas and red bell pepper. DO NOT mix. Cover the Instant Pot with a glass lid and rest the Paella for 2-3 mins. The residual heat will beautifully wilt the veggies without overcooking them. The resting time will also help marry the flavors of the dish in extraordinary way.
Open the lid and gently fluff the paella with the help of a fork in order to mix in the veggies.
Add back the shrimps and garnish the Paella with finely chopped flat leaf parsley.