Tajen samak

Name: Tajen samak (Fish with Sumac Tahini Sauce)
Yield: Serves 4
Cuisine: Syrian
Ingredients: 1 small bunch of flat-leaf parsley (chopped); Juice of 1–2 organic lemons (as desired); 170 ml (⅔ cup) of water; 4–6 garlic cloves (as desired, pressed); Sumac; organic lemon (in slices); 1 tablespoons of ground nutmeg; Salt and pepper; 3 onions (sliced into rings); 2 tablespoons of olive oil, plus extra for drizzling; 700 g (1 lb 9 oz) of white fish fillets; 4 teaspoons of sumac; 150 ml (5 fl oz) of tahini; 1 handful of pine nuts (toasted)