1. Crumble the yeast into a bowl. Stir in the water, salt, oil and sugar. Then stir in most of the flour, reserving some for kneading. Knead the dough until smooth. Cover and let rise for approx. 30 min. Preheat the oven to 225°C.
2. Use a peeler to thinly slice the courgette. Peel the onions. Bring the vinegar, sugar and spices to a boil. Add the onions and cook for approx. 3 min. Let the onions cool, then combine with the courgette.
3. Peel and finely chop the onion for the meat topping. Fry the ground lamb and onions in butter, stir in the tomato purée, cumin and salt. Cook for 3-4 min.
4. Divide the dough into 8 pieces and roll out into mini pizzas. Place the pizza bases on a baking sheet lined with parchment paper. Brush the edges with whipped egg yolk. Cover with the meat mixture and cheese. Bake in the middle of the oven for 7-8 min.
5. Top the pizzas with pickled onions and courgette. Sprinkle with oregano.
Put a baking sheet or pizza stone in the oven and heat until very hot. Prepare the pizza bases on a cutting board sprinkled with flour to make it easier to transfer them to the hot baking sheet/stone in the oven. This process works best with a pizza paddle.