Roast lamb and potatoes boulangere with soup for the following day

Roast lamb and Potatoes Boulangere - the "healthy version" - and some soup

As Sunday Roasts go, this is a really good one for entertaining because all the preparation is up front and everything cooks at the same time for the same amount of time. It also is full on in flavour.

Ingredients
Leg of lamb (allow 300g per person, although typically you are restricted by the size of whatever the shop has)
6 peeled cloves of garlic
10-12 sprigs of rosemary and/or thyme
Potatoes (we used Maris Piper) allow 2 per person
Onions allow 1 per person (red or white onions, depending on what is in your fridge)
100g of butter, chopped
400ml stock (vegetable, chicken, lamb or beef)
Sea salt and ground black pepper 


Instructions
Preheat the oven to 180 degrees

Prepare the lamb
Rub some olive oil and chopped garlic over the lamb. With a small knife, make 6 incisions across the top of the lamb. Put a rosemary/thyme sprig in each of the others.

Prepare the potatoes
Slice the potatoes and onions as thinly as you can without involving your thumb. I use the slicing disc of my Kenwood kMix 894HB, a mandolin works. Layer it in a big, shallow ovenproof dish and put whatever rosemary/thyme sprigs in you have left (I used thyme in this one). Slosh over the stock, dot around the chopped butter and season with the black pepper and sea salt.

Put a wire rack on top of the dish with the potatoes on and put the lamb on the wire rack.

The idea is that rather than put butter/milk/fat into the potatoes, whatever drips down from the lamb adds flavour. Wrap the whole thing in foil, so that there are no gaps. 

 Put the whole thing in the oven for the following amount of time:

Pinkish - 20 minutes per lb of lamb (if you work in kg, 1 kg = 2.2lb)
Less pink - 30 minutes per lb lamb


Soup from the leftover potatoes

Additional ingredients
Lamb stock (simmered the bone with onions, carrots and stacks of rosemary) 
500ml milk
150g dolcelatte (it was leftover from something else, any cheese with a bit of oomph would do, parmesan and/or gruyere for a bit of nuttiness would be nice)

Instructions
The leftover boulangere then became potato and cheese soup (using my kMix soap blender attachment naturally) - I poached the leftovers in milk to soften, added dolcelatte that was leftover from something else and then simmered with the lamb stock. (Note on that - lamb stock can be fatty, so chill after making and then the fat solidifies and you can get rid of it). No seasoning was required because the boulangere had been well-seasoned in the first place.