Mix together the oil, lemon rind, parsley and coriander seeds with plenty of pepper in a bowl. Rub the tuna steaks with the mixture.
Combine the ingredients for the salsa, season to taste and set aside.
Heat a griddle or frying pan until hot and cook the tuna steaks for 1–2 minutes on each side to cook partially. The tuna should be well seared but rare. Remove and allow to rest for a couple of minutes.
Serve the tuna steaks with a spoonful of salsa, a dressed salad and plenty of fresh crusty bread.