Preheat oven to 400 degrees F (200 degrees C).

Spread sweet potatoes onto a baking sheet; spray with cooking spray and season with 1/2 teaspoon salt and 1/2 teaspoon black pepper.

Roast potatoes in the preheated oven until soft, about 20 minutes. Transfer potatoes to a plate and refrigerate until cooled completely.

Whisk lemon juice, olive oil, brown sugar, sea salt, and 1/2 teaspoon black pepper together in a bowl; let rest for at least 5 minutes.

Mix chilled sweet potatoes, mangoes, onion, cilantro, avocado, green onion, and habanero pepper together in a large bowl. Drizzle dressing over potato mixture and toss to coat.