Place the sardines, lemon rind, olive oil, garlic, mint, salt and pepper in a bowl and toss to coat. Set sardines aside to marinate for 30 minutes. Dust the sardines in the flour. Heat a large non-stick frying pan over high heat, add 1 cm of the extra oil and cook the sardines, in batches, for 1 minute each side or until golden and crispy. Serve with the lemon wedges. Serves 4.