Stewed Kidney and Onion with Mustard Sauce
A traditional British offal dish featuring tender stewed lamb kidneys and caramelized onions with tangy mustard sauce. This british-inspired beef ready in about 40 minutes blends lamb kidneys, large yellow onion, butter into a versatile sauce that lifts everything from grain bowls and roasted vegetables to grilled proteins — a small-batch staple worth keeping in the fridge. Each serving lands at about 280 calories and feeds 4, so a small batch covers several meals across the week without taking over the fridge. Tap "Plan a meal with the AI" below to drop this recipe into your week and send the ingredients straight to Instacart. Nutrition values are approximate, calculated from USDA FoodData Central (fdc.nal.usda.gov) — verify against ingredient labels for any health-driven dietary plan.
Ingredients
- 1 lb lamb kidneys
- 1 large yellow onion
- 3 tbsp butter
- 2 tbsp all-purpose flour
- 1 cup beef stock
- 2 tbsp Dijon mustard
- 1 tsp salt
- 1/2 tsp black pepper
- 2 tbsp chopped fresh parsley
Instructions
- Step 1: Rinse and trim 1 lb lamb kidneys, removing any membrane and fat, then slice into 1/2-inch pieces.
- Step 2: Peel and thinly slice 1 large yellow onion.
- Step 3: Heat 3 tbsp butter in a large skillet over medium heat until melted and bubbling. Add the onions and cook, stirring occasionally, for 10 minutes until soft and golden.
- Step 4: Add the kidney pieces to the skillet and sauté over medium-high heat for 5 minutes until browned on all sides.
- Step 5: Sprinkle 2 tbsp all-purpose flour over the meat and onions, stirring constantly for 1 minute to cook the flour.
- Step 6: Gradually pour in 1 cup beef stock while stirring to avoid lumps, bringing the mixture to a gentle simmer.
- Step 7: Stir in 2 tbsp Dijon mustard, 1 tsp salt, and 1/2 tsp black pepper. Simmer uncovered for 10 minutes until the sauce thickens and coats the kidneys.
- Step 8: Remove from heat and sprinkle with 2 tbsp chopped fresh parsley before serving.
Frequently asked questions
How long does Stewed Kidney and Onion with Mustard Sauce take to make?
Total time is about 40 minutes (15 min prep + 25 min cook). A small batch typically covers several meals in the week — store as the recipe directs.
How do I store leftover Stewed Kidney and Onion with Mustard Sauce?
Transfer to an airtight jar and refrigerate for up to 5–7 days. Most sauces freeze well for up to 2 months — portion into small containers or freezer bags so you can thaw only what you need. Stir before serving; cream- or yogurt-based sauces may separate on standing.
Can I substitute ingredients in Stewed Kidney and Onion with Mustard Sauce?
Yes — most ingredients in this recipe have flexible swaps. For oil, use any neutral high-smoke-point oil (avocado, grapeseed, refined coconut). For aromatics, dried herbs at ⅓ the volume of fresh work in a pinch. The full ingredient list is shoppable on Instacart so you can see substitutes in real time.
How do I scale Stewed Kidney and Onion with Mustard Sauce for a different number of people?
The recipe is written for 4 servings. Multiply each ingredient by (your serving target / 4). Cook time stays roughly the same up to 2x; for 3-4x batches, switch from a skillet to a sheet pan or stockpot so the food isn't crowded — overcrowding steams instead of browns.
What goes well with Stewed Kidney and Onion with Mustard Sauce?
British beef like this pair well with a simple grain (rice, couscous, or crusty bread), a quick salad with acid (lemon vinaigrette, pickled onions), and a pan sauce or yogurt-based dip. Tap "Plan a meal with the AI" to get specific side suggestions.
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