From Waitrose:
Cod roe
The roes are the eggs from mature female fish. A full roe consists of two lobes joined together by membrane, the eggs being held together in translucent skin. They can vary in colour from pink to deep red. Fresh Icelandic cod roe is available in Waitrose.
To store: Refrigerate as soon as possible after purchase, either in the original wrapping or in a sealed airtight plastic container and use within 24 hours.
To cook: Place the whole roe in salted boiling water and then simmer for approximately 10 minutes. Drain them and leave to cool. They can be either eaten cold or sliced thickly, coated in seasoned flour and fried in butter or oil until crisp.