Cut the lamb into cubes and marinate in a mixture of olive oil, lemon juice, salt, pepper, paprika, oregano, sumac for at least 1 h, then skewer it on sticks.
On a hot grill or pan, fry the skewers over medium-high heat, turning them often so they don't burn.
For the couscous:
Cut the vegetables brunoise and cook them in a pan with a little olive oil, add the spices, fry them for 30 seconds and then add the couscous. Mix everything well and add hot water over them until they are completely covered. Take the pan off the heat and cover with a lid. The couscous will soon absorb the water and be ready to serve.
For the tzatziki:
Wash and grate the cucumbers, salt them and then squeeze them thoroughly. Chop the dill, crush the garlic and add to the cucumbers, yoghurt and olive oil.
For serving, sprinkle a little sumac over the skewers and couscous and a little olive oil over the tzatziki.