Place the baby potatoes, diced onion and corn in your Instant Pot.
Sprinkle on 1 Tablespoon of the Old Bay Seasoning and add the water or beer.
Secure the lid on your IP and set to manual for 5 minutes. Quick release.
Add the crab, remaining Old Bay and optional hot sauce to the Instant Pot. The crab should sit on top of the vegetables and not be submerged in the liquid.
Secure the lid on your IP and set to manual for 5 minutes. Quick release.
Stir the contents of the Crab Boil and place the lid back on the IP as you prepare the garlic butter.
For the optional garlic butter, melt the butter in a saucepan over medium heat.
Add the garlic and cook for 1 minute, then remove from heat.
Add the lemon juice and chopped parsley.
You can serve the garlic butter on the side for dipping or drizzle over the plated crab and vegetables.