Preheat the oven to 200°C / 390°F.
Toss sweet potato with olive oil, salt, and pepper. Spread it onto a tray. Roast for 20 minutes, flip, then roast for a further 5 minutes until golden on the edges.
If using precooked rice and quinoa, heat in the microwave according to package instructions, then set aside to cool.
To make the dressing, simply combine all of the ingredients in a high-speed blender and blend until smooth and creamy. Set aside.
Combine the arugula, quinoa, rice blend, black beans, onion, feta, pepitas, and avocado.
Pour over dressing on top (any leftover dressing can be stored in the fridge for up to 3 days). Gently toss to combine, and let the salad rest for a few minutes so the rice has time to absorb some of the dressing.