This is an awesome one. I got it from a Swedish cookbook from the 80's:
600 gms/1 lb 4 oz fillet of beef (the middle part), trimmed
1 tbsp salt
1 ½ tbsp brown sugar
2 tsp white pepper, crushed
1 tbsp black pepper, crushed
1 tbsp dried tarragon
1 tbsp dried sage
1 tbsp dried chervil
100 cc/ ½ cup Madeira or Port wine
Mix sugar, salt and pepper and massage well onto the meat. Mix the herbs and roll the fillet in half of the mixture. Moisten a clean kitchen towel with the wine and wrap around the meat. Refrigerate for three days. Turn around a few times a day. Wrap up and scrape off the spices. Rub the meat with the rest of the herbs. Slice paper-thin. Serve chilled with the accesory:
1 half avocado per person, filled with a sauce made of sour cream, some of the marinade, a little lemon and finely chopped fresh herbs.
Picture from the cookbook: