Place carrots and water in a microwave-safe dish. Cover and microwave on high for 3 minutes or until crisp-tender. Add snow peas and onion. Cover and microwave for 45 seconds or until tender; drain. In a bowl, combine the brown sugar, cornstarch, butter, salt and pepper until smooth. Stir into vegetables. Microwave, uncovered, for 45-60 seconds minutes or until bubbly around the edges, stirring once.