Tip the flour into a bowl, saving 1 tbsp for later. Tip in 2 tsp cumin seeds, a pinch of salt and ½ the pot of yogurt. Add 2 tbsp cold water and mix together to form a smooth dough. Cover and set aside.
Finely slice the cavolo nero, discarding any really woody stems. Roughly chop the spinach leaves and stalks. Peel and thinly slice the onion. Pick the leaves from the herbs. Discard the mint stalks. Finely chop the parsley and dill stalks (keep the leaves separate).
Peel and grate the garlic cloves. Whisk with 1 tbsp oil and a pinch of salt. Set aside. Heat your oven to its lowest setting.
Mix 1 tsp sumac with the remaining yogurt and some salt and pepper. Set aside. Finely slice the shallots.
Set a medium frying pan on the heat. Drizzle in 1 tbsp oil. Add the sliced onion and cook for 2 mins. Add the cavolo nero and cook for 2-3 mins till softened. Add a handful of the spinach. Stir to wilt, then add another till all the spinach has been used up. Add the herb stalks and most of the leaves. Stir through the garlicky oil.
Remove the pan from the heat while you prepare the flatbreads. Dust your work surface with the reserved flour. Divide the dough into two balls and roll them into thin flat breads.
Make 4 holes in the wilted veg. Crack a duck egg into each hole. Sprinkle over the shallots. Put the pan on a medium-low heat. Place a lid on the pan and cook for 5- 7 mins till the white is set and the yolk is as cooked as you like.
While the shakshuka cooks, heat a dry frying pan. Cook a flatbread in the hot pan for 2 mins on each side. Place in the warm oven. Repeat with the remaining flatbread. Place it in the oven if your eggs are still cooking.
Spoon the green shakshuka eggs onto two warmed plates. Scatter over the remaining herb leaves and a dollop of sumac yogurt. Dust over a little more sumac. Serve with the warm cumin flatbreads.