1	Place bottarga in a mortar and, using a pestle, pound to a smooth paste. Combine bottarga, bread, onion and lemon juice in a food processor and process until smooth. While motor is running, gradually add oil and process until combined. Season to taste with sea salt and freshly ground black pepper, transfer to a bowl, cover and refrigerate until required.
2	To serve, spread toast generously with taramasalata and top with a slice of bottarga.

Note Bottarga (smoked grey mullet roe) was originally used in taramasalata until it became too costly. It’s available from select fishmongers. Use smoked cod roe if bottarga is unavailable.