This, of course, is not Icelandic, but Icelanders are very fond of salads and sauces based on mayonnaise, so here is a recipe.
makes 200-300 grams (7-10 oz.)
2 egg yolks
1/2 tsp salt
200-300 ml salad (or cooking) oil
1 pinch pepper (optional)
1/2-1 tsp sugar
1 pinch dry, ground mustard seeds (optional)
1-2 tsp vinegar or lemon juice. White vinegar can be used but will make the taste sharp. Flavoured vinegar, such as tarragon, makes the taste more mellow.
Mayonnaise can be made in a blender or a mixer, or by hand, using a whisk and a bowl with a rounded bottom. Egg yolks and oil must be at room temperature. Mixing bowl/blender cup must be clean and dry, and also at room temperature. Choose oil that has little flavour of its own.
Mix and stir the egg yolks with the salt until light and thickened. Add the sugar and the spice, if using (pepper OR mustard) and half the vinegar/lemon juice and mix well. Lemon juice is healthier than vinegar, and mayonnaise made with lemon juice is better in dressings meant for fruit salads.
Start mixing the oil into the egg yolks, first drop by drop, and then, when the oil begins to blend in, in a steady trickle. Stirring must be constant, or else the sauce may separate. The mayonnaise should thicken bit by bit as more oil is added. If it becomes thinner the oil and egg are not mixing, i.e. the sauce is separating. If that happens, stop adding oil, stir the sauce harder and add 1 tsp water or cream. If that does not thicken the sauce, there are two methods you can use to save the sauce:
a) take a fresh egg yolk and put it in a clean bowl, whisk with a little salt and then add the thin sauce in a steady trickle, stirring constantly until the sauce thickens. The continue adding the oil until the sauce is the right thickness.
b) put 1 tbs. cold water and a bit of vinegar/lemon juice in a clean bowl and add the thin sauce in a steady trickle, stirring with a clean whisk. Then add the oil until the sauce is the right thickness.
Home-made mayonnaise should be thick, smooth and shiny. It keeps well in a closed container in a cold place for a few days. Must not be allowed to freeze and must not be kept in the coldest spot in the refrigerator because then it will separate when it is taken out for use.
When putting the mayonnaise away, smooth it into the container and put a tiny amount of water or oil on top so that a film can not form on top.
Spices may be stirred carefully into the sauce before use, and for thinning, whipped cream may be mixed in.
The sauce must be thick if it is to be used for decorating food or in salads that will be used to top bread. Sauce that will be used on food can be thinner and may be made using whole eggs instead of yolks, or eggs and yolks (1 whole egg + 1 yolk).
If you want to enlarge the recipe, follow these guidelines: 100 ml of oil should be used per each egg yolk, or 150-200 ml per whole egg. The eggs can bind more oil than that, but then the mayonnaise will taste oily.