Boil kettle. Pour water into a large saucepan. Cook tortellini following packet directions until just tender.
Meanwhile, heat oil in a large, deep frying pan over medium-high heat. Slice chicken and add to pan. Cook, tossing, for 1 minute. Add capsicum and capers to pan. Cook, tossing, for 30 seconds.
Combine pesto and vinegar together in a jug. Season with salt and pepper.
Add tomatoes to pan. Cook for 30 seconds. Using a slotted spoon, transfer tortellini to the pan with a little of the cooking water. Toss to combine. Add pesto dressing. Cook, tossing, for 2 minutes or until heated through. Add basil. Toss to combine. Spoon pasta into serving bowls. Sprinkle with parmesan and extra basil. Serve.
