Roast Lamb with Onion Gravy

This traditional Roast Lamb is served with a delicious homemade Onion Gravy. This recipe is a guide to mastering the roast lamb so it is beautifully tender and full of flavour in every bite.

This is a recipe for one of my all-time favourite dinners - Roast Lamb. Growing up on a farm in Rotorua it was always special to have a Sunday roast. This recipe produces a delicious onion gravy which goes so well with the sliced lamb and roasted veggies. If you enjoy roast meals, be sure to check out my Roast Pork with Gravy. 

We're so lucky to have such great quality lamb in our New Zealand supermarkets. Add in lots of fresh vegetables and you have the perfect roast. Below I have explained how to use any leftover meat to create a roast lamb pie.

I have kept my lamb recipe super simple and it is coated with olive oil, salt and rosemary. The meat sits on top of the onions so the juices from the roasting lamb create a delicious onion and lamb stock which I use to make homemade gravy from scratch. 

Ingredient notes:

• Lamb: Naturally rich and full of flavour, making it perfect for roasting. Lamb shoulder gives a tender, fall-apart result when cooked slowly, while lamb leg is leaner and slices beautifully. I stock up on a few legs of lamb before Christmas when the prices are low, so we can enjoy this meal as a family all year round.
• Onion: They bring sweetness, richness and that classic homemade gravy flavour everyone loves.
• Rosemary: A classic pairing with lamb - as it cooks, rosemary infuses the lamb and gravy with a delicious aromatic flavour that makes the whole kitchen smell incredible!

Note: Scroll to the recipe card for the ingredients, quantities and the full method.

Step by step instructions:

First of all preheat you oven to 170°C fanbake.

Cut onions into wedges and place them in the base of a oven-proof casserole or cast iron dish. Pour in the water and place the leg of lamb on top of the onions. Brush over olive oil then sprinkle over salt and rosemary. After 2 hours add an extra 1 cup of water to the base of the dish this stops the onions catching on the bottom of the pan.

Peel and chop your chosen veggies then coat in olive oil. Bake on a tray until golden and cooked through. I start my vegetables cooking 1-1.5 hours before serving. The potatoes take the longest to bake so chop them smaller than the pumpkin and kumara. 

After 3-3.5 hours the lamb will be tender and the fat crispy (this will depend on the weight and size of your piece of meat). Remove it from the dish and cover in tinfoil to rest until serving.

Add the dish to the hob on the stovetop and bring it to a simmer. Pour in the stock and cornflour slurry. Simmer stirring until the gravy thickens up, this should only take a few minutes, double the cornflour slurry if needed.

Carve hot lamb and serve with onion gravy, roasted veggies, peas and mint sauce or jelly.

How to make a roast lamb pie:

Once dinner has been served, slice any extra lamb off the bone and cut it into small bite size pieces. Stir this through any leftover gravy then store in an airtight container in the freezer. When you are ready to bake your pie, thaw the pie filling in the fridge overnight. 

Line a pie dish with baking paper and puff pastry, fill with the thawed roast lamb and gravy mix. Top with sliced potatoes sprinkled with salt and a little bit of parmesan cheese. Or you can top it with a simple pastry lid. Bake your pie for at least 30 minutes until the pastry is golden and the pie filling is cooked to piping hot, serve slices of pie with a side of steamed veggies or peas.

Storage:

Store any leftover Roast Lamb with Onion Gravy in an airtight container in the fridge for up to three days. Reheat in the microwave until piping hot.

Top tips:

• If you don't like chunky onions in your gravy you can use a stick blender to blend it until smooth.
• I served potatoes, kumara and butternut pumpkin with my roast lamb. Parsnip, carrots and brussel sprouts would also be delicious.
• If you have any left over lamb simply stir it through the gravy and freeze for later. Then you have a great last minute pie filling you can top with pastry or potato slices and bake until golden and piping hot.

Related Recipes:

Made this recipe?
Please click on the stars below to rate it or, write a review!

---

Thank you for checking out this recipe. I hope you enjoy making and eating it! If you have any questions, queries or feedback, please feel free to leave a comment below.
If you don't already follow me, head over to my Instagram, Facebook or TikTok pages to keep up to date with all my new recipes.
Vanya