Prepare the onion salad - In a small bowl, combine the sliced red onion, lemon juice and chopped coriander. Set aside to marinate while you prepare everything else.
Cook the mushrooms - Heat 2 tbsp of olive oil in a large frying pan over medium-high heat. Add a third of the mushroom mix (a combination of oyster, king oyster, and sliced flat mushrooms). Cook undisturbed for a few minutes to allow browning, then sprinkle 1 tsp of the shawarma spice mix over the top. Flip and add another 1 tsp to the other side. Cook until browned and tender (about 5–6 minutes total). Remove and repeat with remaining batches, adding fresh oil each time - .
Assemble the skewers - Once all the mushrooms are cooked and slightly cooled, thread them onto two wooden skewers.
Make the harissa dressing - In a small bowl or jug, mix together 4 tsp harissa paste and 150ml olive oil until well combined.
Roast the mushrooms - Preheat your oven to 200°C (fan). Place the mushroom skewers on a baking tray and drizzle over the harissa dressing. Roast for 10 minutes until slightly crispy and sizzling.
Assemble the shawarmas - Warm the flatbreads and spread 1 tbsp tahini over each. Add 1 tsp harissa, divide the roasted mushrooms between them, then top with a generous helping of onion salad, 1 tsp garlic aioli, chopped tomato, and cucumber.
Serve immediately - Best served fresh with extra coriander or mint if you like.
