Preparing mussels: Frozen packaged mussels can simply be added to the pot when instructed.

Preparing mussels: Fresh mussels must be soaked in a large bowl of cold water for 20 minutes. This cold water soak releases sand and grit from inside the shell. If any shells are open, tap them and wait 30 seconds for the shell to close. If the shell doesn't close, discard it (this means your live mussel is dead). Once they have been soaked, debeard mussels and scrub the outside of the shells. Rinse under cold water until it runs clean

Before getting started prepare your fresh mussels according to the notes section above. Frozen mussels can be used as is.

Set the Instant Pot to saute on high for 3 minutes. Add the butter and melt completely. Add diced shallots and tomato and saute for 2 minutes, stirring frequently. Add minced garlic and cook 1 minute more.

Turn off saute and pour in the dry white wine. Deglaze the bottom of the pot with a wooden spoon to ensure no bits of onion, garlic and tomato are stuck.

Add the mussels to the Instant Pot. They can be stacked, but make sure to gently put them into the pot so the shells don't crack. Combine the vegetable broth and juice from the lemon in a mixing glass and pour it over the mussels. Sprinkle with the crushed red pepper.

Close the lid and seal. Set to pressure cook (manual) on high for 5 minutes for frozen mussels and 3 minutes for fresh mussels. When done steaming, complete a controlled quick release of the pressure.

Open the lid and transfer the mussels to a serving bowl using tongs. Discard any mussels with closed shells. Pour the rest of the wine sauce that's in the pot over the mussels and season lightly with freshly ground salt if desired. Top with fresh torn parsley and serve warm.