Add butter to the Instant Pot and select Sauté.
When butter is melted, add onion to the pot and sauté until soft.
Add wine to the pot and deglaze by using a wooden spoon to scrape any brown bits from the bottom of the pot.
Add stock, cream, salt and herbs to the pot and stir to combine.
Carefully fan the pasta in the pot (this helps prevent clumping) and ensure it is completely submerged.
Add the halved cherry tomatoes in a single layer--do not stir.
Press cancel and secure the lid.
Select Pressure Cook and set the time for 5 minutes.
When the cooking program is finished, let the pressure release naturally for 5 minutes, then quick-release the remaining pressure and remove the lid.
Gently stir the pasta, breaking up any clumps.
Fold in smoked salmon pieces and serve immediately garnished with freshly ground pepper and additional herbs.