Preheat oven to 425 degrees F (220 degrees C) and line a large baking sheet with parchment paper.
Cut potatoes into even 3/4-inch chunks, place in a large bowl, drizzle with oil, and add taco seasoning, garlic powder, smoked paprika, salt, and pepper. Toss well to coat evenly.
Spread potatoes in a single layer on the baking sheet. Roast for 25 minutes, flip or stir, then roast another 15-20 minutes until deeply golden and crispy.
While potatoes roast, heat a large skillet over medium heat. Cook diced onion for 3-4 minutes until softened.
Add ground beef and cook, breaking it up, until browned (about 5-7 minutes). Stir in garlic and taco seasoning, cook 1 minute more.
Pour in water or broth and add beans if using. Simmer 4-5 minutes until thickened. Season with salt and pepper.
Assemble bowls: Add a generous base of crispy potatoes to each bowl, sprinkle with cheese while hot, top with warm taco filling, then add lettuce, tomatoes, avocado, sour cream, salsa, cilantro, and a squeeze of lime.
Serve immediately while hot and crispy.