"Create a dairy-free, gluten-free, corn-free version of Chef John's Salisbury Steak inspired by the linked Allrecipes recipe. Keep it beginner-friendly, quick/easy (15-30 min active time if possible), for a household of 3, using minimal processing and imperial units. Avoid all dairy, gluten, and corn ingredients, and also avoid nuts, soy, sesame, and shellfish. Include a savory mushroom gravy if appropriate, using safe substitutes for Worcestershire if needed (must be gluten-free and corn-free). Make it flavorful, low-inflammation friendly, and suitable for an omnivore family. Provide ingredients and clear steps."