Cube your sweet potatoes and cook them in a pot of water until fork tender. You can also use a microwave steamer and cook for 5 minutes unitl they are tender.
Drain and cool in the refrigerator for 10 minutes.
In the meantime cut up your red onion, olives and peppers.
In a separate smaller bowl, mix your lemon juice, olive oil, garlic, oregano, salt and pepper.
When your potatoes are cooled, mix in the rest of the ingredients and dressing and toss well.