Add the drained sardines to bowl and carefully chop them. Avoid mashing as you want to keep some texture, then set aside. Add a teaspoon of sugar to the white wine vinegar and give it a mix.

Spread the mix liberally on two of the sardine fillets and place the other fillets on top to create a 'sandwich'. Season the sardine skin with sea salt. Preheat the grill to hot. Heat a little oil ...