Loj (rom means literally cream, or as we understand it - the caviar or roe of the fish) is a fresh-water mountain fish that as far as I know, isnt available in the UK (any potential suppliers please let us know). You can use any caviar you like as a substitute but try to avoid the salty and unpalatable roe of the lumpfish - its much too salty. Fish with potatoes are a mainstay of the Nordic countries and as is often the case, the simplest peasant dishes are the most memorable. The caviar offered originally in Scandinavia were orangey-red very small-sized moist fish eggs called Lojr?m Difficult to find outside those shores, we have substituted Beluga caviar, regarded as the mother of all caviars - and certainly our favourite. (Although you could Oscietra or Sevruga if you preferred). Look for the label malossal, which indicates low-saltiness, and is a guide to top quality. Recently, there has been quite a lot of Iranian caviar for sale and generally it is quite good. As for the potatoes, by all means start off the baking process in a microwave (indeed it is one of the few times it is useful - as it heats from the inside out, the middle does not have to be hard) - but it is imperative to complete the process in a regular oven to get the skin nice and crispy. Dry and prick the baking potatoes (King Edwards or Maris Piper are good varieties) and bake in a hot oven (180?C/450F/gas mark 8) for about 45-55 minutes. It is OK to start off the potatoes in a microwave for the first 15 minutes or so but replace in a regular oven for the last part of cooking time (20 minutes at least) to crisp-up the skin and get the interior to get a fluffy texture. When soft in the very middle, split the potatoes along the length and season with salt and fresh ground black pepper, dot with a couple of cubes of the butter and swirl a couple of large tablespoons of soured cream into the split. You should note that the best type is the runny cream, prepared in the eastern European tradition, not the stiff creme fraiche found in France. Quickly spoon a couple of spoonfuls of caviar on top of each potato and the dish is ready. Some people favour chopped egg or onion as additional garnishes, but in this instance, it detracts from the simple appeal of this idea.