1. Wash, dry, and halve the bell peppers, then remove the seeds and membranes. Press the pepper halves down slightly and place them, skin-side up, in the Air Fryer basket. Roast the bell pepper at 200°C (390°F) for about 15-18 minutes. It is fine if the peppers turn black in some spots. You can also do this in the oven (see notes).

2. Remove the roasted peppers from the Air Fryer and place them immediately into a sealable container (or freezer bag). Let them cool and steam in their own moisture for about 15 minutes – this makes the skin easier to peel off later.

3. While the peppers cool, peel the onion and cut it into thin wedges. Hard-boil the eggs (if using). Drain the liquid from the tuna.

4. Peel the skin off the bell peppers – it is okay if small bits remain. Cut the bell peppers into bite-sized pieces or strips, then combine them in a bowl with the onion wedges and tuna.

5. Mix the olive oil and vinegar, add the mixture to the bowl, and season with some flaky sea salt and pepper to your liking. Roughly break up the boiled eggs and arrange them on top of the salad. Mix everything once more at the table just before serving.