Salisbury steak was a member request and is pure comfort food - great for cold weather. Not really "steak," the dish is made of lightly seasoned ground beef patties seared in a pan and served with a rich gravy. Smarts: The gravy served with this version of Salisbury steak includes sliced onions and mushrooms for added depth. If you prefer a smooth gravy, feel free to skip one or both of these additions to the gravy.
Onions - (If prepping right before cooking, get potatoes boiling before continuing with prep.) Thinly slice onions. (Can be done up to 5 days ahead)
Make Salisbury spice mix - Combine salt, oregano, garlic powder, onion powder, and black pepper. (Can be done up to 5 days ahead)
Make gravy mixture - Combine stock, water, Worcestershire sauce, and mustard. (Can be done up to 5 days ahead)
Mushrooms - Slice mushrooms, if not pre-sliced. (Can be done up to 3 days ahead)
Form patties - Combine beef with Salisbury spice mix, panko, and ketchup. Form into 4 oval patties (for 4 servings; adjust if customizing). Try not to overwork the mixture as this will make the “steaks” more dense. (Can be done 1 day ahead)
Place potatoes into a saucepan and cover with cold water and some salt. Cover and bring to a boil. Simmer uncovered for 12 to 15 minutes until potatoes can be easily pierced by a knife. Drain and let sit in a colander for ~5 minutes to let the steam escape (this creates creamier potatoes vs. liquidy potatoes).
Use a masher to mash steamed potatoes with sour cream, butter (portion for potatoes), and some salt. Set aside, covered to keep warm.
Heat a saute pan or skillet over medium-high heat. Add oil and then patties to heated oil. Cook patties on one side until golden brown, 2 to 3 minutes. Flip patties and continue cooking until cooked to your liking (similar to burgers) - 2 to 3 minutes more for medium-rare, 3 to 4 minutes more for medium, 5 to 6 minutes more for well-done.
Set patties aside, covered to keep warm. Return pan to heat.
If the pan is dry, add a splash of oil. Add onions and mushrooms and saute until soft, 3 to 4 minutes.
Add flour and stir until no dry spots of flour remain, ~2 minutes.
Pour gravy mixture over onions / mushrooms while whisking. Bring to a simmer. Reduce heat to low-medium and simmer gravy until it thickens slightly, 3 to 4 minutes.
Place frozen peas in a microwave safe bowl and cover with a damp paper towel. Defrost until no longer frozen and then cook on high until heated through, ~1 minute. Remove and toss with butter (portion for peas) and some salt and pepper.
Serve Salisbury steaks over mashed potatoes with gravy spooned over top. Serve peas on the side. Enjoy!