For the sweet potatoes, preheat oven to 350 degrees F, and line a baking sheet with parchment paper. Mix together the sweet potatoes with the oil, cumin, and salt in a large bowl, then spread evenly onto the prepared baking sheet. Roast 40-45 minutes, tossing halfway through, until tender and browned.
Meanwhile, for the cilantro-lime rice, bring water and salt to a boil in a saucepan. Add rice, turn heat down to medium-low, and then simmer, covered with a lid, until rice is tender, about 15 minutes. Remove from heat and allow to sit for a few minutes, then fluff with a fork. Add lime juice and cilantro, then stir to combine and set aside.
While the rice and sweet potatoes are cooking, stir together the black beans and spices in a small bowl.
Next prepare the guacamole by mashing together the avocados, lime, cilantro, and salt until creamy.
When the potatoes and rice have finished cooking, assemble the bowls by evenly dividing the sweet potatoes, rice and beans among four bowls. Top with the guacamole, shredded lettuce, salsa, and cheese, then serve!