Preheat the oven to 400°F (200°C). Peel and dice the sweet potatoes into 1-inch cubes, toss with olive oil, salt, and pepper, and spread on a baking sheet. Roast for 25-30 minutes until golden and tender.

In an Instant Pot, combine 1 cup of rinsed brown rice with 1 ¾ cups of water and a pinch of salt. Seal and cook on high pressure for 22 minutes, then allow a natural release for 10 minutes, and fluff with a fork.

In each bowl, start with a base of brown rice, add kale or spinach, and then layer with black beans.

In a blender, combine the mango, tahini, lemon juice, and garlic powder. Blend until smooth, adjusting with water if necessary.

Drizzle the mango tahini sauce over each bowl and serve immediately, with extra lemon on the side if desired.