Add the cauliflower florets to a small pan of boiling water. Simmer for 4-5 minutes until fork tender. Drain away the water and set aside to steam dry.
Whilst the cauliflower dries you can prepare the BBQ sauce. Add the passata (tomato sauce), tamari sauce, syrup, paprika, garlic powder, cumin, cinnamon, mustard and olive oil to a small bowl. Stir together well to combine.
Add the par cooked cauliflower to a large bowl. Spoon over the BBQ sauce. Stir everything together well to combine, so that the cauliflower is evenly coated in the marinade.
Arrange the cauliflower in the base of the air fryer basket. Ensure the cauliflower florets are in an even layer to ensure they all cook through. Set the basket in the air fryer.
Set the temperature to 375 degrees Fahrenheit and set the timer for 10 minutes. After this time, turn the cauliflower pieces over. Set the timer to cook for a further 8 minutes. The cauliflower should be tender in the center and crisp and golden at the edges.