Combine margarine and milk in a small saucepan, set over low heat and stir until melted. Remove from heat, add the saffron and let the mixture cool down until lukewarm.
When the misture reaches body temperature add the fresh yeast and stir to melt.
In a bowl, combine flour, sugar and salt. Pour in yeast mixture and stir to combine. When the dough comes together, knead it into a ball. Put the ball back into the bowl, cover with cling film and leave to rest for 40 minutes. The dough should be very soft but not sticky, adjust the amount of flour if it's too sticky to handle.
Preheat the oven to 250°C. After 40 minutes, take a small amount of dough and roll it into a sausage about as thick as a pencil. Swirl both ends to create a reversed S-shape and place each on an oven tray lined with baking paper. Leave enough room between the ubns as they will grow larger as they bake.
Lightly beat the egg and brush every bun with eggwash. Press a raisin into each swirl. Bake in the preheated oven at 250°C for 5-6 minutes.