Dice the tuna into 1 cm pieces. Add to a glass bowl along with olive oil. Mix well to coat thoroughly. Set aside.

Prepare the dressing by adding lemon zest and juice, fermented chili, capers, flaky salt, black pepper, and half of the chives to a small bowl. Mix well.

Add the dressing to the tuna and mix well.

Spoon the tuna tartare into a shallow serving bowl. Top with the remaining chives and an extra drizzle of olive oil. Check the seasoning and add a tiny pinch of flaky salt if needed.

Serve immediately with the toasted bread slices.