This old-fashioned oven casserole turns cubed beef, ketchup, and dry onion soup mix into a rich, glossy supper. The covered bake gives the beef time to soften, while the final uncovered stretch concentrates the tangy, savory sauce. It is especially good over mashed potatoes, noodles, or rice.
Why this three-ingredient dinner works
Chuck beef becomes tender with a long, gentle bake. Ketchup supplies sweetness, tang, and body; the onion mix provides seasoning. Together they make a sauce that clings to each piece of beef without a separate gravy step. Use a baking dish large enough to spread the meat evenly.
Ingredients
- 2 pounds beef stew meat or beef chuck, cut into bite-size pieces
- 1 cup ketchup
- 1 packet dry onion soup mix
How to make Oven-Baked Beef Mercer
1. Prepare the oven and dish
Heat the oven to 325°F (165°C). Lightly grease a 9 × 13-inch glass baking dish. Cut any unusually large pieces of beef so the cubes cook at a similar pace.
2. Arrange the beef
Spread the beef in the dish in an even layer. Keeping the pieces loosely spaced helps the sauce coat them all.
3. Make the glaze
Stir the ketchup and dry onion soup mix together in a small bowl until no dry pockets remain. Spoon the mixture over the beef and turn the pieces gently to coat.
4. Bake until tender
Cover the dish tightly with foil and bake for 1 hour. Remove the foil, stir the beef, and continue baking for 30 to 45 minutes. The beef should be fork-tender and the sauce thickened around the edges. If the meat is still firm, cover it again and bake in 15-minute increments.
5. Rest and serve
Let the casserole rest for 5 to 10 minutes. Stir once more and spoon it over mashed potatoes, egg noodles, or rice. Add green beans, carrots, or a simple salad to balance the meal.
Variations & Tips
- Choose the right cut: Chuck or stew meat with some marbling softens more reliably than very lean beef.
- For a sweeter finish: Stir 1 to 2 tablespoons brown sugar into the sauce before baking. This adds a fourth ingredient.
- For a fuller casserole: Add small, evenly cut carrots or potatoes during the last 45 minutes and check that they are tender before serving.
- Make ahead: Assemble the dish a few hours in advance, cover, and refrigerate. Let it stand while the oven preheats, then bake.
- Watch the sauce: If it thickens too quickly during the uncovered stage, cover the dish again. A small splash of water can loosen it if needed.
Storage and reheating
Cool leftovers promptly and refrigerate in a covered container for up to 3 to 4 days. Reheat gently, stirring in a splash of water if the sauce is too thick. Freeze cooled portions for up to 2 to 3 months and thaw in the refrigerator before reheating.
