It is different from granola and oatmeal, in that the oats are raw, and not grilled nor cooked. The original recipe recommends cream or condensed milk, which I replace with yoghurt to make it a bit lighter. Also, instead of hazelnuts or almonds, I sometimes add pecan nuts which I like very much. I usually prepare a big bowl of müesli for the whole week, it keeps very well in the fridge for a couple of days.
The recipe is a bit approximate so you'll have to try and adjust it to your taste :-)
Recipe for Birchermüesli (4 portions)
250 g rolled oats
2x the volume of water (8 dl approx)
250 g plain yoghurt
juice of one lemon
honey or sugar to taste
a handful of raisins
a handful of chopped nuts (pecan, hazel...)
extra: some berries (raspberries, strawberries...)
Soak the oats in the water for a few hours or overnight. Remove the water (use a sieve/strainer) and put in a bowl. Add the yoghurt and mix. You can add more or less depending on how "solid" you want your bircher to be. Add the lemon juice bit by bit until you start to taste it (it should make tiny bubbles). If you want to sweeten your bircher, I recommend you add some liquid honey here (or sugar).
Grate (or dice) an apple, add it along the raisins and the chopped nuts to the bircher and mix. The nuts are not necessary but I find that they add a crunchy side to the soft müesli. Serve and decorate the bircher with some berries if you have some, it tastes even better then :-)
Note: you can add more or less of the fruits and nuts to your preference!