Toast coriander and fennel seeds in a small frying pan over medium heat until fragrant 30 seconds, crush spices in a mortar and pestle.
Combine with remaining ingredients except oil, season to taste. Transfer to a 1.5 litre capacity sterilised glass jar.
Top with oil and refrigerate to marinade (2-3 days).
Serve with your favourite crackers, lemon mayonnaise, coarsely chopped coriander and Bloody Mary or beer (optional).