Preheat the oven to 200 degrees C/392 F. Cook the quinoa according to packaging instructions (this should take around 20 minutes).
In a large mixing bowl, stir together the cubed pumpkin, salt, pepper and maple syrup until the pumpkin is evenly coated. Transfer to a baking sheet covered with parchment paper and bake for 15-20 minutes, until the pumpkin is soft.
Add the pumpkin, cooked quinoa, chickpeas, carrot, red onion, carrot ribbons, petit pois, mashed avocado and balsamic vinegar to a large mixing bowl. Stir well to combine, seasoning with more salt and pepper and garnishing with walnuts if desired. Serve straight away or chill for an hour for a cold salad.**
* Simply ribbon the carrot with a vegetable peeler. ** The salad lasts 3-4 days in the fridge in an airtight container.