Preheat the oven to 190°C/375°F/gas mark 5.
Grate the zest from 2 of the lemons and set aside in a small bowl.
Squeeze the juice from the zested lemons.
Put the sardines in an ovenproof dish.
In a bowl, mix the olive oil, lemon juice, garlic and oregano.
Drizzle this mixture over the fish and season with black pepper.
Put in the oven for 25-30 minutes.
Cut the remaining lemons into wedges.
Serve the sardines hot, sprinkled with lemon zest and accompanied by the lemon wedges.