Preheat oven to 400°F/200°C.
In a large bowl toss together sweet potato cubes, oil, salt, cinnamon and pepper.
Line a baking sheet with parchment paper.
Lay the sweet potatoes out in a single layer on the tray. Bake for 20 minutes.
Take out the tray, use a thin spatula to flip the potatoes, drizzle lemon juice, and maple syrup, and toss again.
Bake for another 10 to 20 minutes or until the sweet potatoes are soft and tender.