Heat oven to 400ºF (200ºC). Toss the florets in olive oil and spread in a single layer on a baking sheet. Season with red pepper flakes, salt and pepper.
Roast until the broccoli is slightly charred, about 20 minutes. Sprinkle the broccoli with the vinegar and set aside.
For the quinoa:
Bring the vegetable stock to a boil over medium heat, then stir in the quinoa and chickpeas.
Reduce the heat to medium-low and cover, simmering until stock has been absorbed, about 15 minutes. Fluff with a fork and keep covered until ready to use.
For the salad:
Add arugula to a large mixing bowl followed by the quinoa and chickpeas. Toss with the creamy cashew dressing until combined. Add the roasted broccoli, avocado and radish and toss once more.
Divide among bowls and top with the nutritional yeast and serve.