Lean lamb hot pot

Ingredients

• 700g well-trimmed lamb leg meat (or leg steaks)
• 2 tsp sunflower oil
• 2 medium onions, peeled and thinly sliced
• 5 medium carrots, peeled and thickly sliced (about 300g prepared weight)
• 3 tbsp plain flour
• 600ml lamb stock, made with 1 lamb stock cube
• 1 tbsp fresh thyme leaves or ½ tsp dried thyme
• 1 rosemary stalk or ½ tsp dried rosemary
• 2 tbsp Worcestershire sauce
• flaked sea salt
• freshly ground black pepper
• 3 medium potatoes (about 500g)