Place the quinoa in a fine-mesh strainer and rinse it thoroughly under cool running water.
Add the rinsed quinoa and water or broth to a medium saucepan. Bring the mixture to a boil.
Reduce the heat to low, cover, and simmer for approximately 15 minutes, or until the liquid has been absorbed.
Remove the saucepan from the heat and let the quinoa rest, covered, for 5 minutes. Fluff it with a fork, then allow it to cool.
While the quinoa cools, add the black beans, corn, bell pepper, cherry tomatoes, red onion, jalapeño, and cilantro or parsley to a large bowl.
To make the dressing, whisk together the lime juice, olive oil, cumin, chili powder, garlic powder, salt, and black pepper.
Add the cooled quinoa to the bowl with the beans and vegetables.
Pour the lime dressing over the quinoa salad and toss until everything is evenly combined. Taste and adjust the lime juice, salt, or seasonings as needed.
Cover and refrigerate until ready to serve. Add pumpkin seeds and avocado as toppings immediately before eating, if desired.