Select the “saute” function on your instant pot and allow to heat up.
Add the butter, onion, and garlic and saute for 2 minutes, then add the oregano, salt, and pepper.
Saute another 1-2 minutes, until the onion is starting to soften.
Add the chicken stock and canned tomatoes.
Put on the lid and set to high pressure for 10 minutes.
Once finished, use the quick release method to depressurize, then remove the lid.
Blend the soup with an immersion blender, until smooth and lump-free.
Stir through the cream and serve hot, topped with a drizzle of cream and fresh basil.