Preheat the oven to 400°F (200°C).
In a large bowl, toss diced sweet potatoes with olive oil, chili powder, cumin, smoked paprika, garlic powder, and sea salt.
Spread evenly on a parchment-lined baking sheet and roast for 20-25 minutes, flipping halfway through, until golden brown and tender.
While the sweet potatoes are roasting, cook quinoa or brown rice according to package instructions. Fluff with a fork. Heat black beans in a small saucepan over medium heat, seasoning with a pinch of salt and cumin for extra flavor.
In serving bowls, divide quinoa or brown rice as the base.
Add roasted sweet potatoes and black beans on top.
Sprinkle with fresh cilantro and squeeze a wedge of lime over everything.