An easy recipe with ingredients that most people have handy.
Cook potatoes in a small saucepan until tender. Drain. Place potatoes back in pan. Heat the milk and butter in microwave until hot. With a potato masher, roughly smash the potatoes while adding hot liquid until combined and set aside.
In a bowl, combine tuna, egg, green onions, mayonnaise, bread crumbs, and lemon juice. Form into patties. Allow to refrigerate and become firm for 10 minutes.
Heat oil over medium-high heat, cook patties until golden brown, about 2 minutes on each side. Serve with potatoes.