Preheat the oven to 400°F. Cut the sweet potato (no need to peel) into rounds about ½ inch thick. Place them on a baking sheet and toss with 1 tsp vegetable oil and taco seasoning. Roast until tender, about 18 to 20 minutes.
Chop the roma tomatoes and add to a medium bowl. Chop the cilantro. Add just half the chopped cilantro to the bowl. Peel and small dice the red onion. Deseed and mince the jalapeño. Add as much as you’d like of each to the bowl. Zest the lime and set zest aside. Halve the lime and add the juice to the bowl. Season with ¼ tsp salt and toss the pico de gallo well to combine.
Drain and rinse the black beans. Add the black beans to a small saucepan over medium heat and cook until hot, about 3 to 5 minutes. Mash into a paste with the back of a fork and season with salt and pepper.
Add 2 cloves garlic to a food processor and pulse until well chopped. Working in batches if necessary, add the cauliflower florets and pulse until you reach an even, rice-like consistency. Place a large nonstick skillet over medium-high heat with 2 tsp vegetable oil. Once hot, add the cauliflower rice and cook, stirring occasionally, until tender and brown in places, about 5 minutes.
Once the cauliflower rice is finished, remove from heat, fluff with a fork, and add the lime zest, remaining chopped cilantro, and a pinch of salt. Stir to combine.
Divide the cauliflower rice between large shallow bowls. Top with the roasted sweet potatoes, mashed black beans, and pico de gallo. Dollop each bowl with sour cream and sprinkle with any remaining minced jalapeño.