Preheat oven at 400 F (200 C)
Wash the lamb with a bit of wine. Pat dry
In a small bowl mix 2 tsp fine salt and 1 tsp or so ground pepper.
Rub the lamb with the salt and pepper mixture.
Cut the 4-5 garlic cloves in half and place them in a small bowl. Sprinkle with 1/2 tsp salt and pepper and toss.
Make deep slits in the lamb (on both sides) and push in the halved garlic cloves.
Rub 1 tablespoon dry oregano all over the lamb. And then rub the lamb with 3-4 tbsp olive oil and set aside
Prepare the potatoes. Peel and soak in water if you have time for about 15-20 minutes (you can do this while you are preparing the lamb). Drain and rinse.
Cut the potatoes in thick long wedges and place in a bowl.
Drizzle the potatoes with ½ cup olive oil, and add 1-2 tbsp oregano, 3 tbsp lemon juice. ¾ tsp salt, 3 cloves, 3 allspice, fresh ground pepper, and 2 whole garlic cloves. Toss well, so potatoes are coated with the olive oil.
Spread the potatoes in a large enough pan so that they are in one layer. Place the leg of lamb on top of the potatoes, top side facing down. Pour enough hot water in the corner of the pan tilting the pan so that water spreads throughout the base of the pan, covering the potatoes halfway. Cover with aluminum foil and put it in the oven.
Roast for 15-20 minutes and then lower to 340 F (170 C), remove the foil and roast for another 30 minutes or more until lamb has turned brown flip the lamb and cook another 30 minutes or until brown and cooked through.
Once lamb is done, you can remove it and continue roasting the potatoes until all the water has been absorbed and only the oil is left in the pan.
Let lamb and potatoes rest for 15 minutes before serving.