Strain the roast pan juices through a sieve into a measuring cup. Let it sit for 2-3 minutes or until the fat on top separates from the juices below. Skim off the fat with a large spoon, reserving 1 tablespoon for the gravy (Note 1).
1/2 cup lamb roast pan juices, 1 tbsp lamb roast fat
In a small saucepan, add 1 tbsp of the roast fat, 1/2 cup of the roast pan juices, and the stock. Bring it to a simmer on medium heat.
3/4 cup stock
Meanwhile, combine 4 tbsp of pan juices and the flour in a small bowl to make a slurry.
2 tbsp flour
Once the juices are simmering, stir in the slurry. Keep stirring until the sauce thickens and reduce the heat to low. This will take 2-3 minutes (Note 2).
Remove the saucepan from the heat and season the lamb gravy with salt and pepper to taste (Note 3).
1/4 tsp salt, 1/8 tsp ground black pepper
Notes
Note 1: Don't discard the lamb fat, aka drippings. It's great for frying or roasting root vegetables or to get other lamb dishes under way.Note 2: If you have lumps in the sauce, simply strain the lamb gravy with a sieve before serving.Note 3: For a darker-colored gravy, add 1 tsp of dark soy or Worcestershire sauce before seasoning the sauce.Storage: You can store leftover gravy in an airtight container in the fridge for up to 4 days. Alternatively, you can freeze it in one lot or smaller convenient portions for up to 3 months.