*Aleppo pepper is available at specialty delis / artisanal grocers / spice stores. If you cannot find Aleppo pepper simply substitute with 1 tsp sweet paprika and ¼ tsp cayenne pepper. Mix together.Preheat oven to 180˚C.Bring a large pot of salted water to the boil.Cook the spaghetti until it is just shy of al dente.
For the quick pickled onions
Combine all the ingredients in a glass jar and give it a good shake. Make sure the onions are submerged. Leave at room temperature while preparing the rest.
For the yoghurt sauce
Combine all the ingredients together and taste to adjust seasoning. Keep in the fridge until serving.
For the mushrooms
Stir the softened butter and harissa paste together until well combined. Taste the harissa paste you are using for seasoning - you may or may not need to add a little extra salt and pepper.
Preheat oven to 200°C with the fan on. Line a large baking tray with baking paper.
Place portabellos on prepared tray and brush generously with harissa butter.Roast for about 7-10 minutes or until just tender.
While the mushrooms are roasting, warm or toast some flatbread and prepare the other toppings.Serve harissa butter mushrooms piled onto warm flatbread with generous dollops of the spicy lemon yoghurt.
Scatter everything with fresh coriander leaves and pickled onions. Squeeze over some fresh lime juice and enjoy!