I have been making one type or another of gravadlax at Christmas for a few years now. Clearly is it very popular in some countries but I think has not properly caught on yet in the UK.
Gravlax or grav(ad)laks is a Nordic dish consisting of salmon that is cured using salt, sugar, and dill. Gravlax is usually served as an appetiser, sliced thinly and accompanied by hovmästarsås (literally “maitre d’hôtel sauce”, also known in Sweden as gravlaxsås, in Norway as sennepssaus, literally “mustard sauce”, and in Denmark as rævesovs, literally “fox sauce”), a dill and mustard sauce, either on bread or with boiled potatoes. I think I really like mine with just a simple salting on a thin slice of toasted sourdough toast.
Next of course you are asking what is the Science behind this, well salt and sugar curing is an age-old way of preserving meat and fish and enhancing flavour. It is also easy to do at home.
It works by drawing water out of microbial cells that cause food to spoil, killing them or slowing their growth. The meat or fish also loses moisture, concentrating its flavour. This is further improved in meat by enzymes continuing to break down proteins over time. This produces glutamate creating an enhanced “umami” taste and the salt also dissolves myosin strands so tenderises.
Traditionally, smoking was a combination of drying and adding chemicals from the smoke to the fish, thus preserving and adding flavour to the final product. However, much of the fish smoked today is exposed to smoke just long enough to provide the desired flavour with little, if any, drying.