Set your oven to 400⁰F/200⁰C, combination steam setting. If your oven has variable steam settings, use 60%. If not, don't worry! Just set to combi steam at the correct temperature and the oven will figure out the humidity for you. Line a baking tray with parchment paper. Spread the sweet potato onto the tray and cook for about 20 minutes or until tender and lightly browned. Remove and tip into a bowl.
If you’re making the whole meal immediately, change oven setting to 212⁰F/100⁰C on steam setting (it will take a few minutes to cool down to this temp but I find it’s pretty close by the time I’m ready to put the couscous in).
Heat the oil in a frypan over medium heat and fry the onion until translucent. Remove from heat, scrape into the bowl of sweet potato and set aside. If you’re not going to make the rest of the dish until later, cover and refrigerate.
Add the pepitas and almonds to the frypan and cook until toasty and golden. Remove from heat and set aside.
Mix the ras el hanout, salt and pepper in a small bowl. Rub half of this mixture over the lamb fillets and set them aside.
Mix the other half of the spices with the stock. Put the couscous and stock into a tray (I use the same one I cooked the sweet potato in, minus the parchment paper. It’s all about minimizing dishes!). Steam for 15 minutes, then stir and add the dates, onions and sweet potato and steam for a further 5 minutes. Remove from oven, set aside and change setting to 450⁰F/230⁰C on combination steam (again, 60% steam if you have the option).
Cook the lamb for about 5 minutes or until cooked to your liking. Mine took exactly 5 minutes to cook to medium-ish (what you see in the photos).
While the lamb is cooking, mix the nuts and seeds, coriander and feta through the couscous ready for serving. Rest the lamb for a few minutes before slicing and serve everything warm with natural yoghurt and a green salad on the side.