Cut capsicums in half from top to bottom and seed them.
Brush inside and tops of capsicums with 2 teaspoons olive oil.
Set aside.
In a frying pan, heat remaining oil over medium-high heat for 30 seconds.
Add onion, squash and mushrooms.
Stir-fry for 5 minutes until onions are tender.
In a medium bowl, combine tomatoes, tomato sauce, Italian seasoning, smoked paprika, salt and pepper.
Preheat air fryer at 180°C for 3 minutes.
Evenly distribute mixture among the capsicum halves.
Place two halves in the air fryer basket.
Cook for 8 minutes.
Transfer to a serving plate.
Continue with remaining halves.
Serve warm.