IT WAS THE PRACTICE on Sundays in many towns throughout France to leave a piece of meat with the town boulangère (baker) to be roasted. The roast would be dropped off at the baker’s shop on the way to church and picked up, fully cooked, on the way home.
The baker would place the meat on racks in his bread ovens and position baking dishes filled with sliced potatoes and onions beneath the roasts to catch their juices while cooking. Sometimes the bakers would roast the meat directly on top of the sliced potatoes and onion. The potatoes were simply moistened with water, but would pick up flavor from the dripping fat and meat juices. Thus, the origin of the name à la boulangère, or “in the style of the baker.”
I have specified that the onions be sautéed, a step that slightly increases your work but substantially increases the flavor of the finished dish.