Prepare the potatoes: Preheat the oven to 425°F (220°C). Wash and peel the potatoes, then cut them into roughly 1-inch chunks.
Soak for extra crispiness: For especially crispy potatoes, place the chunks in a large bowl of cold water for 20–30 minutes. Drain thoroughly and pat completely dry with paper towels.
Season the potatoes: Toss the dry potatoes with 1 tablespoon of oil, half of the chili powder, and a pinch of the salt.
Roast: Arrange the potatoes in a single layer on a baking sheet. Roast for 20–25 minutes, turning halfway through, until golden brown and tender in the center.
Cook the taco filling: While the potatoes roast, heat a large skillet over medium-high heat. Add the remaining chili powder, salt, garlic powder, and black pepper. Toast for about 30 seconds until fragrant.
Brown the beef: Add the ground beef and cook, breaking it apart with a spoon, until browned and cooked through.
Add the corn: Stir in the frozen corn and water. Bring the mixture to a gentle simmer, cover, and cook for about 5 minutes, until the corn is hot and the liquid has reduced slightly.
Assemble the crispy loaded potato taco bowl: Divide the hot roasted potatoes between serving bowls. Spoon the seasoned beef and corn mixture over the potatoes.
Add toppings: Finish with shredded cheddar, guacamole, pico de gallo, and sour cream, as desired. Serve immediately.