Preheat oven to 200°C. Line a large baking dish with aluminium foil and lightly coat with non-stick cooking spray. Toss the sweet potatoes in the baking dish with half the oil to coat, then spread in an even layer. Roast until tender and lightly browned, about 20 minutes.
Whisk the remaining oil, lemon juice, orange juice, honey, salt and pepper in a small bowl. Taste dressing and add 1 tsp lemon juice, if desired.
Toss warm potatoes and dressing in a serving bowl. Add rocket, orange segments, onion and raisins. Toss to combine.