Add quartered onion, potatoes, corn, and sliced andouille sausage to the pot. Mix together seasoning and 6 cups water. Pour into the pot. Add a little more water just to cover the vegetables in the pot. 

Place the lid on the pot and set valve to sealed position. Press pressure cook or manual button and set timer to 6 minutes. Once the instant pot stops counting release the pressure. 

Open the lid and add peeled and deveined shrimp to the pot. Give it a good stir and place the lid back onto the pot. Set valve to sealed position and then press pressure cook or manual button and set to 2 minutes. 

Once the pot stops counting release the pressure and it's ready to serve with extra spice on the side.