Grate courgette and microwave for 3 minutes, cool slightly, and squeeze out excess water.

In a skillet, heat olive oil and sauté leek or onion for 3-4 minutes until translucent. Add minced garlic and cook for another 30 seconds.

In a food processor, combine fresh tuna, the sautéed mixture, ginger, lemongrass, optional red chili, salt, black pepper, olives, mustard, and sesame oil. Pulse until blended but chunky.

Transfer mixture to a bowl, add drained courgette and optional mayo, and mix gently with hands.

Form mixture into about 12 meatballs and place on a tray.

Preheat air fryer or oven to 175°C (350°F). Cook meatballs for 8 minutes in air fryer or bake on a tray for 8-12 minutes until golden.

Let rest for a minute, then serve with salad or in a lettuce wrap.