Preheat oven to 180 degrees C. Line two oven trays with baking paper. Cut pumpkin into 1cm-thick slices, then cut slices in half. Spread pieces on prepared trays. Spray with olive oil. Season. Roast for 30-35 minutes or until lightly golden.
Meanwhile, bring a large saucepan of water to the boil. Add buckwheat and quinoa and cook for 10-12 minutes or until tender but still nutty. Drain and rinse under cold water.
Reduce oven to 160 degrees C. Combine pepitas, cashews, paprika and sriracha in a bowl. Spread on an oven tray lined with baking paper. Spray with olive oil. Bake for about 10 minutes or until crisp. Allow to cool.
To make dressing, place all ingredients in a small jug and whisk with a fork until combined.
Place buckwheat and quinoa in a bowl. Add pumpkin, mint, rocket, pepitas and cashews. Season and stir to combine. Spoon into a serving dish. Drizzle with dressing just before serving.
Raw buckwheat is a gluten-free seed that is not related to wheat. It is high in fibre and essential nutrients and is found in the health food section of supermarkets and health food stores.