How to Cook a Lamb Roast

Choosing and cooking a roast can sometimes be a daunting prospect. From selecting the right type of roasting joint for the occasion and number of people, to preparing your roast for optimal flavour, to ensuring that the temperature of your oven is correct, it can sometimes be a little bit overwhelming!

Explore our Lamb Roasting Joint Range

However, our guide here will go through all of our roasting joints for roast lamb options, with detailed introductions for each of our roast lamb products, and instructions on how to properly cook each type of joint.
So whether you are a novice cook wanting to learn something new or a seasoned chef looking to experiment with a different type of roast, this guide will tell you everything you need to know about how to cook a roast lamb.
So from how to choose a lamb roast, to how to season a lamb roast, to how to cook a lamb roast, read on as we go through each type of lamb roasting joint.

 

Before you Roast Your Lamb

Before you roast your Lamb it is really important that you take your roast out of the fridge and give it an opportunity to reach room temperature. This is because if the centre of the roast is too cool, this will affect the speed at which the lamb roast cooks and may result in the lamb being undercooked, and also the outside may be overcooked by the time the middle of the lamb reaches the ideal temperature for consumption. Simply remove from the fridge, place in a roasting tray, and cover with cling film, aluminium foil, or a tea towel. If using a tea towel make sure to wash it afterwards to prevent cross contamination between raw meat and other areas of your kitchen. For a large lamb roast, around 2kg, this process may take up to an hour. Make sure to rearrange your oven shelves so that the roast will be cooking in the centre of your oven, and before placing your roast in the oven ensure that it has reached the temperature needed. You can season your lamb first then leave it to the side to allow the roast to reach room temperature.

 

How to season a Lamb Roast

There are many ways to season a lamb for roasting. One of the easiest, tastiest, and most popular options is to use a mixture of salt, rosemary, and garlic. First, remove the cloves from the garlic bulb, then carefully peel each clove. Chop each clove very roughly, you don’t want to chop it too fine as the garlic may burn in the oven when roasting the lamb. Then take your rosemary and remove the thin leaves from the sticks, and discard the sticks. To season the lamb to make small incisions into the skin of the roast in regular intervals. Then simply place a bit of a garlic clove and a few rosemary leaves into each incision. After you have done this, season the lamb with a little bit of salt. You don’t want to add too much salt as this will dry out the meat and make it less juicy and tender. As the lamb roasts, the flavours of the seasoning will be released slowly into the meat.

 

While you cook your Lamb Roast

While your Lamb Roast is cooking, you may wish to baste the meat. When a roast is cooking the oven, juices from the meat will start to gather in your roasting tin or tray. These can be used as the base for an excellent gravy, but another option is to baste your meat. This involves taking the roast out of the oven at regular intervals, then using a baster, spoon, or ladel to gather some of the juices and pour them back over the meat. This process is fantastic for making sure that your roast has an excellent flavour and does not dry out. Ideally you want to do this 2 or 3 times during the roasting process. Make sure that you keep your oven door closed while you do this so that the heat doesn’t escape.

 

After you roast your lamb

When your lamb roast has finished cooking, the next step in the roasting process is to allow your roast lamb to rest. When cooking, the meat often loses moisture which can be used to baste the meat. Taking some time to allow the meat to rest gives the roast an opportunity to soak up some of the lost juices, which results in a juicier and tastier roast that is also easier to carve. Transfer from the roasting tin onto a clean warm plate or chopping board, then cover it with foil so that the lamb does not cool down too much. For a very small roast, like a rack of lamb for two you only want to rest for about 10 minutes. Most roasts will benefit from 30 minutes of resting time after cooking.

Types of Lamb Roast and cooking times

Boneless leg of Lamb

Boneless leg of lamb is one of the more popular roast lamb options in the UK. It is easy to cook and has plenty of flavour, as well as being very easy to carve from as there is no bone in the way.

Cooking Method

Temperature:
180C/160C for a fan oven/Gas Mark 4
Time:
30 minutes per 500g, then another 30 minutes

 

Lamb Shoulder Mini Roast

Shoulder is also a popular roasting joint option. It benefits from a slightly longer cooking time than a leg roasting joint, and still has plenty of flavour. This joint is ideal for serving two people.

Cooking Method

Temperature:
180C/160C for a fan oven/Gas Mark 4
Time:
60 minutes per 500g, then another 30 minutes

 

Lamb Shoulder Boneless

This boneless shoulder option serves 4 people, and is very easy to carve due to the lack of bone.

Cooking Method

Temperature:

170C/150C for a fan oven/Gas Mark 3
Time:
40 minutes per 500g, then another 40 minutes

 

Lamb Shanks

These Lamb Shanks serve 1 person per shank. To cook these, you will want to wrap them loosely in kitchen foil for the first two hours then finish them off. The timings below are for two shanks.

Cooking Method

Temperature:
160C/140C for a fan oven/Gas Mark 3, then 180C/160C for a fan oven/Gas Mark 4
Time:
Wrap in foil, then cook for 2 hours at 160C/140C for a fan oven/Gas Mark 3. Remove the foil and place back in the oven at 180C/160C for a fan oven/Gas Mark 4 for a further 45 minutes, turning twice.

 

Saddle of Lamb Boneless

Lamb saddle is made from the loin on both sides of the animal. It is a premium roast that is incredibly tender, and is fantastic for entertaining.

Cooking Method

Temperature:
215C/200C for a fan oven/Gas Mark 5, then 190C/180C for a fan oven/Gas Mark 4
Time:
Cook for twenty minutes at 215C/200C for a fan oven/Gas Mark 5, then reduce to 190C/180C for a fan oven/Gas Mark 4 then cook for a further 30 minutes per 500g

 

Leg of Lamb on Bone

This Lamb roast option is one of the most traditional and recognisable. It is a spectacular roast to look at, and is full of flavour. You will want to wrap the Lamb loosely in foil for the first 20 minutes in the oven, then remove the foil and cook for the rest of the remaining time.

Cooking Method

Temperature:
200C/180C for a fan oven/Gas Mark 6
Time
20 minutes wrapped in foil, then 30 minutes per kilo