Make the spice mix by combining freshly ground black peppercorns, dried tarragon, salt, and onion powder. I recommend combining the spices in a small bowl so that the steaks get an even mix of all spices.
Pat the steak dry and divide the spice mix evenly on each steak
Toss the steak in the mix until it is coated (top, bottom, and side)
Heat a frying pan or cast iron skillet to medium-high heat
Add 2 tbsp butter and allow it to sizzle
Cook steak for 4 minutes per side (or 1-3 minutes longer depending on how done you'd like the steak to be. Mine were medium well).
Remove the steak from the pan and set aside. I like to make a tent with foil to allow my steak to stay warm and cook a little longer
Turn the pan to medium low
Add remaining tbsp of butter to the pan
Add shallots and garlic to the pan and cook until translucent (~2 minutes)
Add water and scoops of bone broth. Mix so that the powder is fully incorporated and without lumps.
Add sour cream, heavy cream to the pan and cook until it thickens like a sauce (~3 minutes)
Stir in parsley and lemon juice. Top the steak with the sauce and serve immediately.