- Place potatoes in a large saucepan. Cover with cold water. Bring to the boil over medium-high heat. Reduce heat to medium. Cook for 15 to 17 minutes or until tender. Drain and cut into quarters.
- Place potatoes in a large bowl. Add tuna, celery, tomato and spinach. Toss to combine.
- Pour over dressing. Season with salt and pepper. Mix well and serve.