To make Instant Pot tomato soup, start by chopping the tomatoes into quarters. Slice the onions and garlic. (To use canned tomatoes, see notes at the end)
Start with the saute mode on the Instant Pot. Add the olive oil and butter (if using) to the inner steel pot. Saute the bay leaf for a few seconds.
Add in the sliced garlic and onion and saute for 1-2 minutes.
Add the chopped tomatoes and stir for a minute.
Add the stock cube (if using) and 1 cup of water. Alternatively, use 1 cup of vegetable stock, if that is a more convenient option for you.
Stir the contents of the pot. Fix the lid of the Instant Pot. Cancel the sauté mode. Make sure the vent is in lock position. Cook on high pressure (HP) for 10 minutes.
Allow the pressure to release naturally or you can release the pressure manually after another 15 minutes. Remove and discard the bay leaf.
Transfer the contents to a blender and blend to a smooth puree. You can also use an immersion blender for the same purpose. Check for salt level and adjust accordingly. If you have used the vegetable stock cube, it contains some salt already which is why it is better to check in the end and adjust the levels.
Transfer the blended soup to the Instant Pot and in Saute mode, let it come to a simmer. Add freshly ground black pepper and finely chopped herbs (I use basil and flay leaf parsley).
Serve with toasted slices of sourdough bread.