Preheat your oven to 400°F (200°C). Toss the diced sweet potatoes with olive oil, a pinch of salt, and black pepper. Spread them on a baking sheet. Roast for 20-25 minutes until tender and slightly caramelized.
While the sweet potatoes roast, brown the ground beef in a large pan over medium-high heat. Drain any excess fat. Stir in the taco seasoning and a quarter cup of water. Cook for 5-7 minutes, breaking up the meat with a spoon, until the liquid evaporates.
In a mixing bowl, combine the corn kernels with the mayonnaise, fresh lime juice, and chopped cilantro. Add the cotija cheese, minced jalapeño (if using), and green onions. Mix well to combine all ingredients.
Divide the roasted sweet potatoes and seasoned ground beef among serving bowls. Spoon a generous amount of the street corn mixture over each bowl. Garnish with additional fresh herbs or a drizzle of spicy honey if desired. Serve immediately for the best taste.