Warm roast beef and mustard salad

Leftover roast beef is warmed briefly with potatoes and green beans in a sharp mustard dressing.

This recipe makes 4 servings and takes about 12 minutes to prepare plus 18 minutes to cook. Metric and imperial quantities are alternate measurements, so use one system rather than adding both. If you change the yield, keep the pan size and thickness of the food in mind: a crowded pan steams food and a deep baking dish can extend the cooking time.

Equipment

Set out large frying pan, small bowl, saucepan, tongs. A wide pan gives moisture somewhere to evaporate; for an oven dish, leave space between pieces so heat can circulate. Use separate board and knife surfaces for raw protein and foods that will be eaten without further cooking.

Ingredients

You will need: new potatoes, halved: 600 g (1 lb 5 oz); green beans, trimmed: 250 g (9 oz); olive oil: 30 ml (2 tbsp); wholegrain mustard: 20 g (1 tbsp); red wine vinegar: 15 ml (1 tbsp); cooked roast beef, sliced: 350 g (12 oz); watercress: 80 g (3 oz). Gather the ingredients before heating the pan so the aromatics do not burn while a measurement is being found.

• new potatoes, halved — 600 g / 1 lb 5 oz
• green beans, trimmed — 250 g / 9 oz
• olive oil — 30 ml / 2 tbsp
• wholegrain mustard — 20 g / 1 tbsp
• red wine vinegar — 15 ml / 1 tbsp
• cooked roast beef, sliced — 350 g / 12 oz
• watercress — 80 g / 3 oz

Method

Read the full method once, then prepare the ingredients in the order listed. Keep raw and ready-to-eat ingredients separate, and wash hands and equipment after raw-protein contact.

Step 1

Boil new potatoes for 12 minutes until tender. Add green beans for the final 3 minutes, then drain.

Step 2

Whisk olive oil, wholegrain mustard, and red wine vinegar in a bowl.

Step 3

Warm the potatoes and green beans in the frying pan for 2 minutes. Add cooked roast beef for 1 minute only, just until warmed.

Step 4

Toss with mustard dressing and watercress, then serve immediately.

Cooking and safety check

If reheating leftover roast beef, heat it until steaming hot throughout before serving. A time estimate and a browned surface do not prove that the centre is cooked. Use a suitable food thermometer where the ingredient or local guidance requires one, and follow the package or official instructions for the specific food.

Substitutions that respect the dish

A substitution should preserve the recipe’s job, not merely its colour. Rocket replaces watercress. Dijon mustard can replace wholegrain mustard; both contain mustard. Use cooked lamb instead of roast beef. Tenderstem broccoli replaces green beans.

• Rocket replaces watercress.
• Dijon mustard can replace wholegrain mustard; both contain mustard.
• Use cooked lamb instead of roast beef.
• Tenderstem broccoli replaces green beans.

Allergen notes

This recipe contains or may contain mustard. Check every packaged ingredient because formulations and cross-contact warnings vary.

Common mistakes and how to correct them

Use one troubleshooting change at a time. If the centre is undercooked, return it to the appropriate heat and check again rather than relying on the outside colour. If the pan is dry, add liquid gradually; if it is watery, reduce uncovered. Texture may also reflect crowded equipment, a different ingredient size, or a changed batch quantity.

• Do not boil green beans too long; they should stay bright and crisp.
• Warm beef briefly to prevent it toughening.
• Whisk dressing again if it separates.

Leftovers and storage

Store undressed potato and beef salad separately for up to 2 days. Reheat the beef and potatoes until steaming; add watercress fresh.

Serving ideas

These sides and finishes suit warm roast beef and mustard salad without changing the recipe itself.

• Pickled shallots
• Crusty bread
• Horseradish crème fraîche

Frequently asked questions

Can I serve it cold?

Yes, use chilled beef and potatoes, then add the dressing.

What beef works?

Thinly sliced cooked roast beef is best.

Related recipes and tools

Browse the related recipes for a different appliance, pace, or ingredient pairing. Use the serving scaler only after checking the stated yield, and use the storage guide before deciding whether to save a portion. Related links help with the next decision; they do not make this recipe suitable for every diet or kitchen.