For the monkfish, mix the crème fraîche, harissa and lemon juice together in a bowl large enough to accommodate the monkfish. Spread the marinade over the fish, cover and refrigerate for 2 hours.
For the flatbread, mix the flour and salt in a large bowl. Soften the yeast in the warm water with the sugar. Add to the flour along with the yoghurt and olive oil. Knead for 15 minutes, or until the dough is smooth and elastic. Cover and rest in a warm place until doubled in size (this will take about an hour).
Divide the dough into balls approximately the size of tennis balls. When ready to use, roll into flat rounds.
Cook in a dry, hot frying pan until blistered on both sides. Wrap in tea towels and keep warm in a low oven until ready to serve.
Preheat the oven to 250C/230C Fan/Gas 9.
For the monkfish, scrape off most of the marinade and place on a baking tray. Roast for 6–8 minutes, depending upon the thickness. Set aside to rest.
While the monkfish is resting, combine all the salad ingredients in a bowl.
To serve, mix the zaatar ingredients together with the olive oil to make a loose paste. Spread some of the zaatar mixture over the flat breads and lay on a serving boards or plates. Scatter the salad over the top and slice the monkfish to scatter over.