"Adapt the recipe 'Beef and Mushrooms with Smashed Potatoes' into a dairy-free, gluten-free, and corn-free version. Keep it beginner-friendly, quick/easy, and suitable for a household of 3. Use minimal processing, imperial units, and avoid dairy, gluten, and corn ingredients entirely. Preserve the general flavor profile of beef, mushrooms, and smashed potatoes, and include safe substitutions for butter, milk/cream, flour, and any corn-derived ingredients if present. Make it low-inflammation friendly where possible."