I discovered this dish while holidaying on the Italian seaside which combines smoked swordfish and carbonara. Essentially the guanciale is replaced by the smoked swordfish. A genuine carbonara is always made with eggs and not cream so the combination of eggs and smoked fish (think smoked salmon or kippers) is a classic one. It also means that pescatarians (vegetarians who eat fish) can also enjoy this deliciously creamy, smokey toothsome pasta dish. While I have only seen this dish with swordfish in Italy, making it with smoked salmon would be equally delicious albeit not authentic. This substitution may be necessary however as smoked swordfish outside of Italy is rather rare while smoked salmon is ubiquitous. If I am making this for lunch for the children, I sometimes add a handful of frozen peas to the cooking water during the last 3 minutes of cooking.