Fillet and butterfly the sardines (or ask your fishmonger to do this when you buy them).
Rinse the sardines and let them drain while you prepare the marinade. Chop the garlic, parsley and coriander, tip into a large bowl, and add the lemon juice, salt and the spices.
Coat the fillets with marinade on both sides, then press them together in pairs, open sides together. Lay on a plate, drizzle over the remaining marinade, cover with clingfilm, and marinate in the refrigerator for 1 hour.
Heat the oil in a large frying pan, dredge the sardines with flour on both sides, and fry over low heat, turning once. Transfer to kitchen paper to absorb the excess oil before arranging on a serving platter.