Brush 2 chicken thighs with olive oil and rub each with 1/2 teaspoon Ras el Hanout. Refrigerate for 2 hours. Soak your clay pot (Römertopf) in water and grease the bottom with a little olive oil.
Clean carrots, cut in half lengthways, then cut into strips; layer in the bottom of the clay pot. Peel potatoes, cut into bite-sized pieces, add to pot and season with a little salt. Cut paprika into bite-sized pieces, cut tomatoes into eighths, halve onion and slice, clean leek and cut into rings, cut celery into small cubes, cut ginger into small cubes, and chop half the parsley. Add paprika, tomatoes, onion, leek, celery, ginger, and parsley to the pot. Sprinkle 1 teaspoon Ras el Hanout, 1 pinch coriander, 1 pinch cumin, and salt over vegetables. Halve plums and add them. Add lemon juice. Season chicken thighs with a little salt and place on top of the vegetables.
Cover pot with lid and bake at 180°C (356°F) for 70 minutes without preheating the oven. Remove lid, increase oven temperature to 200°C (392°F), and bake uncovered for 25 minutes until chicken is golden and internal temperature reaches 74°C (165°F). Chop remaining parsley and sprinkle fresh parsley on top. Serve.