Rinse basmati rice well.
Soak for 10 minutes and then drain.
Heat a generous drizzle of olive oil in a large saucepan with a lid.
Add the onion and cook until soft.
Add the garlic and ginger and cook until fragrant.
Add the garam masala, turmeric, chilli powder, cinnamon, cardamom and curry leaves.
Cook for a few minutes to bloom the spices.
Add the diced tomato and cook until they begin to break down.
Add the drained basmati rice and gently pour over the vegetable stock.
Bring to a simmer and place the lid on the saucepan.
Cook very gently for 15 minutes until the rice is tender and all the stock has been absorbed.
While the rice is cooking, heat a large frying pan over medium-high heat.
add a drizzle of olive oil and cook the Portabellinis until golden.
Add the cherry tomatoes, curry leaves and curry powder.
Cook briefly, tossing everything together until the tomatoes just begin to soften. Season well. Fluff the rice and spoon over the extra mushroom and tomato topping.
Serve the biryani with yoghurt on the side and enjoy!