Prepare the Liver:
In a glass or plastic bowl, place the beef liver.
Pour milk over the liver and allow it to soak for 30 minutes to 1 hour. This step helps tenderize the liver and mellow its flavor.
Remove the liver from the milk and pat it completely dry with paper towels.
Season and Dredge:
Generously season both sides of the dried liver with the prepared Seasoning Blend.
Add the remaining Seasoning Blend to the 1 cup of flour and mix thoroughly to create the seasoned dredge.
Sauté the Onions:
Heat a cast-iron skillet over medium-high heat and add the cooking oil.
Add the sliced onions and fry until they are golden brown and fragrant, approximately 6 minutes.
Remove the onions from the pan and set them aside. Sprinkle the cooked onions lightly with a pinch of sea salt.
Sear the Liver:
Dredge each piece of seasoned liver in the seasoned flour, ensuring both sides are fully coated.
Working in batches (to avoid overcrowding the pan), sear the liver for 3–4 minutes per side until a golden crust forms.
Remove the seared liver and set it aside. Repeat the process until all pieces are cooked.
Make the Gravy:
Reduce the heat to low. Carefully drain off approximately half of the oil from the skillet.
Add a scoop of the seasoned flour (the remaining dredge) to the pan. Whisk it into the hot oil, scraping up all the browned bits (fond) from the bottom of the pan to create a roux.
Add the bay leaf and slowly pour in the vegetable stock, whisking continuously until the gravy is slightly thickened and smooth.
Season the gravy with the 2 teaspoons of cayenne pepper and 2 teaspoons of seasoning salt, adjusting to your taste preference.
Simmer and Finish:
Return the seared liver to the gravy in the pan.
Reduce the heat to a gentle simmer. Cover the skillet and cook for about 12 minutes, gently shaking the pan occasionally to prevent sticking.
Just before serving, stir the reserved, sautéed onions back into the pan. Serve immediately.