Preheat oven at 375 degrees Fahrenheit (190 Celsius).
Peel and cut the potatoes in pieces (as noted above).
In a large bowl mix the sweet potatoes with the olive oil, salt and pepper (I usually mix with my hands).
Spread the potatoes in one layer in a pan. Add a small clove of garlic cut in half.
Pour the orange juice in one corner and tilt the pan so it goes everywhere.
Add 3-4 tablespoons of boiling water again in the corner and tilt the pan. Do not just pour the water or juice over the potatoes, that will rinse off the oil.
Roast for about 20 minutes and then lower the temperature to about 320 Fahrenheit (160 Celsius) and roast for another 30-40 minutes.