Add all the steak ingredients, except the butter, to a large mixing bowl. Combine the ingredients with your hands, being sure not to over-mix. Shape into 6 patties and set on a platter.
Let the steaks rest (for breadcrumbs to absorb moisture) while slicing the mushrooms and onion.
In a medium-size bowl, whisk the gravy ingredients together, except the cornstarch and water, and set aside.
Set the Instant Pot to Saute, Normal Temperature. Once hot, add the butter. Brown the steaks on both sides, in batches (about 2 minutes). Wash the platter, and return the steaks to the platter. Set aside.
Add the mushrooms and onions to the Instant Pot, and saute lightly for two minutes. Add the gravy mixture to the pot, and scrape the bottom of the pot to loosen any bits (bits = flavor!).
Press the Cancel button and add the steaks on top of the mushrooms and onions. It's okay if they overlap in the pot.
Lock the lid on and set the Instant Pot to Manual High Pressure for 15 minutes. The valve on top should be set to Sealed. When the cooking time ends, let the pressure release naturally for 15 minutes. Then perform a quick release (turn the valve on the top to Venting) to be able to open the lid.
Remove the steaks to the serving platter.
Whisk the cornstarch into the cold water. Then add the mixture to the gravy in the Instant Pot, whisking to avoid lumps. Saute the gravy until you reach the desired thickness (about 5 minutes for me). Pour the gravy over the steaks.
Serve the steak and gravy with mashed potatoes (recipe coming later this week) or egg noodles--Jovial makes great egg noodles. I've also been serving this meal with an easy side salad.
*If you avoid gluten and can't find gluten-free panko, I think almond flour or almond meal may work as the binder. I'm not sure if it will sub 1:1. **I use Bonafide Provisions Beef Broth found in the freezer section at Whole Foods. You may also make homemade beef broth, using the slow-cooker or Instant Pot. ***I prefer thick gravy, so I went with 3 tablespoons of water and cornstarch. Helen used 2 tablespoons of water and cornstarch. You can always add more cornstarch and water (1:1 ratio) during the last cooking step if the gravy isn't as thick as you'd like. Arrowroot starch may work as a sub. This site provides directions for subbing arrowroot for cornstarch. This recipe makes 6 steaks and a good amount of incredible gravy. One recipe is able to feed my family of four (two adults and two young kids) for two nights, or one night and one lunch.