Preheat the oven to 180 degrees (top/bottom heat).
Peel the onions and cut into wide, long strips. Halve the tomatoes, remove the stalk and roughly quarter. Peel the potatoes and cut into 1-2 cm wide, oval slices (see photo above).
Brush the bottom of an ovenproof pan (or oven dish) with a little oil. First place the potatoes side by side on top, then add the onions and tomatoes. Drizzle with olive oil and salt and bake in the oven for approx. 20-25 minutes.
Meanwhile, place the meat in a bowl with the remaining ingredients for the meatballs. Mix everything well and form flat meatballs (adjust the size to the oven dish/pan).
Remove the vegetables from the oven and spread the meatballs in between. Bake for a further 15-20 minutes.
Meanwhile, place the tahini, lemon juice, garlic and spices in a bowl. Mix everything well, the tahini should start to thicken slightly. Don't worry, this is normal.
Remove the meatball pan from the oven. Carefully drain the juices/liquid from the pan into a bowl and collect.
Carefully add the hot liquid to the tahini and mix well until you have a smooth, homogeneous sauce. If necessary, the stock can be diluted with a little water. Season to taste with salt & pepper. Add more lemon to taste.
Turn the oven up to 200 degrees and bake for approx. 10 minutes (until it starts to simmer slightly).
Meanwhile, melt the ghee in a small pan, add the pine nuts and fry over a medium heat until the pine nuts are lightly golden brown.
Remove the mince and vegetable tahini pan from the oven and scatter the hot pine nuts over the simmering tahini sauce.
Top with chopped parsley and enjoy with fresh flatbread or Arabic rice.