Preheat the oven to 200°c/390°f.
Coat the chopped peppers and zucchinis with 1 tbsp of the olive oil and plenty of salt and pepper. Bake them in the preheated oven until soft and caramelised, around 20-25 minutes.
Meanwhile, rinse the quinoa in a sieve under a running tap, then add it to a saucepan along with 1½ cups/375ml salted water. Bring it to the boil, then reduce to a simmer. Cover and continue to simmer for around 20 minutes, or until all of the water is absorbed. Fluff up the quinoa with a fork, then re-cover the pan.
Next, heat the remaining oil in your pan over a medium heat, then add the diced onion. Fry it for 5 minutes until softened, then add the garlic and fry for a further 2 minutes until it’s aromatic.
Add the chopped mushrooms to the pan, stir to combine, and turn the heat to medium high. Continue to fry them for 5 minutes until they start to release moisture.
In a blender or jug with an immersion blender, blitz the chopped tomatoes to a pulp. Alternatively, you could grate the whole tomatoes (if you don’t have a blender or don’t fancy the washing up!).
Add the tomato pulp to the pan along with the tomato paste and herbes de provence. Give it all a stir, then simmer for 10 minutes.
Add the roasted zucchini and peppers to the pan, stir to combine, then simmer for 10 minutes more to allow the flavours to meld.
Finally, stir through the chopped basil and season to taste with salt and black pepper, then serve with the cooked quinoa.