My sister makes this every spring, and the meat is so tender you can cut it with a spoon using only 4 ingredients.

Serve the sliced pork straight from the white casserole dish, generously spooning the savory onion gravy over each portion.
Variations & Tips
If you prefer, you can swap the cream of mushroom soup for cream of chicken or cream of celery for a slightly different flavor while still keeping it to four ingredients. For a deeper onion flavor, use one and a half packets of onion soup mix on the meat and reserve the rest to stir into the soup mixture. If your pork loin is on the small side (around 2 pounds), start checking for tenderness at about 2 hours so it doesn’t overcook. For a little browning on top, remove the foil for the last 20 minutes of baking, but only if the meat is already tender. If you like more gravy, add an extra 1/2 to 1 cup of water to the soup mixture and bake as directed; the sauce will still thicken as it cooks. Leftovers can be shredded into the gravy and reheated on the stove for an easy hot sandwich filling over toast or biscuits. To keep the spirit of the recipe—simple and springtime-friendly—avoid adding extra ingredients to the dish itself, but feel free to brighten the plate with fresh herbs or a squeeze of lemon on your side vegetables.