Serves: 40 tostadas1) Put the chopped fish in a wide shallow dish and sprinkle over the oregano, salt and lime juice. Leave this to marinate for 8 minutes.
2) Drain the fish; it will have made a milky liquid. Add the spring onions, jalapeno and coriander and stir gently together.
3) You can either put teaspoonfuls onto little toasts and sprinkle over some more coriander, or put the ceviche into a bowl and serve with tortilla chips.
Recipe from Nigella Express by Nigella Lawson (published by Chatto & Windus) Visit Nigella's site.