Rinse the quinoa under cold running water in a fine-mesh strainer. Then, heat 2 cups of water in a medium saucepan until boiling. Add the rinsed quinoa, reduce heat to low, cover, and simmer for about 15 minutes or until the liquid is absorbed. Fluff with a fork and let it cool.

While the quinoa is cooking, peel and dice the sweet potato. Boil the sweet potato cubes in a pot of salted water for about 10-15 minutes or until fork-tender, then drain and set aside to cool.

Peel and dice the carrots and beets. You can steam them together for about 5-7 minutes until tender but still crisp, or you can roast them in the oven at 400°F (200°C) for about 20-25 minutes with a drizzle of olive oil and a pinch of salt.

In a large bowl, combine the cooked quinoa, diced sweet potatoes, carrots, beets, and spinach. Toss gently to combine.

Slice the cherry tomatoes in half and add them to the bowl along with the raspberries, blueberries, and cubed avocado. Toss gently to avoid smashing the berries.

Now, let's prepare the yogurt dressing. In a small bowl, mix the yogurt with the olive oil, a pinch of salt and pepper, stirring until smooth and creamy.

Slice the boiled eggs in halves and place them on top of the salad. Drizzle the yogurt dressing over the salad, then sprinkle with sunflower seeds and walnuts.

Serve immediately or refrigerate for about 30 minutes to let the flavors meld. Enjoy your vibrant, healthy Rainbow Quinoa Salad!