Preheat oven to 425 degrees F
In a bowl, mix sweet potatoes, onion wedges, salt, pepper, garlic, and olive oil. Toss to coat. Spread in a lightly oiled shallow roasting pan.
Roast mixture in preheated oven, turning now and then, until the vegetables are soft and golden brown, about 30 minutes. Adjust seasonings, if necessary.
Garnish with pomegranate arils and/or chopped pecans, if you wish, before serving.