Add the olive oil to the bowl of the Instant Pot and press the saute button. Once hot, add the onion and a pinch of salt and saute until the onions are soft and fragrant, about 5 minutes. Add the garlic and cook for an additional 1 minute.
Turn the saute button off and add the beans, vegetable broth, tomatoes, tomato paste, salt, and red pepper flakes. Don’t stir (best if tomatoes remain on the top as they can scorch on the bottom).
Cover the machine and press the manual button, cooking on high pressure for 40 minutes. Allow the pressure to release naturally. If the beans aren’t done cooking, cook on high pressure for another 5 minutes, then manually release the pressure (repeat if they’re still too firm).
Open the lid and stir the mixture well. Taste and adjust the seasoning, as needed.
Serve the beans over toast and top with crumbed feta and basil.