Preheat your oven or air fryer to 180°C (350°F). Place the aubergine on a baking tray and roast for about 30 minutes, or until the flesh is soft. Test with a skewer - it should slide in easily.
Let the aubergine cool slightly, then scoop out the flesh and transfer it to a small food processor.
Add the sardine fillet, garlic, cumin, lemon juice, cayenne, salt and pepper. Blend for a few seconds until the mixture is creamy but still has some texture.
Add the lemon zest and parsley, then blend briefly again. Taste and adjust seasoning to your preference.
Let the spread rest for about 10 minutes to allow the flavours to develop. Serve on sourdough toast, crackers or alongside fresh vegetables.
Keeps well in the fridge for up to 2 days.