Add 560g bread flour, 95g spelt flour and 15g salt. Give it a mix with your hand so that it's good and well mixed.
Pour in the milk mixture and add 150g starter on top.
Mix the dough so that all flour is completely hydrated and let the dough rest for 30 minutes.
Bulk fermentation
Perform four sets of stretch and folds spaced out by 30 minutes.
Let the dough rise until it's increased about 50%, then place the dough in the fridge until the following day. It took about 5 hours for me from the first stretch and fold.
Dividing and shaping the dough - next day
Remove the dough from the fridge and divide it into twelve equally sized pieces at around 100 grams of dough.
Shape each dough piece to a ball by pushing the dough up into the middle of the ball, then turn the ball about 20° and repeat until you have a taut surface.
Place the dough balls on a baking sheet lined with parchment paper and let them rest for fifteen minutes.
Then do a final shape of each roll by putting it onto your unfloured counter, putting your hand over the top of the ball like a claw, and moving it in circles, making it perfectly round.
Place back on the cookie sheet and let them rise for about one and a half hours covered with a damp tea towel.
Make the topping
Preheat your oven to 200°C/390°F/Gas mark 6 (use fan-assist if you have it) with an empty pan on the bottom.
Make the topping by placing 7g active dry yeast, 100g lukewarm water, 105g rice flour, 15g brown sugar, 14g neutral oil, 14g toasted sesame oil and 4g salt in a bowl. Mix with a whisk to combine.
The mixture must be spreadable, so adjust using a small amount of water or rice flour to make it a thick, spreadable consistency if it's not already at that stage.
Put an equal amount of topping on each bun and spread it using a pastry brush.
Bake the rolls
When the oven is hot, boil a kettle of water and pour it into the pan, and put the baking sheet in the oven on the middle rack. Close the oven and let it bake for 20 minutes.
Check the rolls after 20 minutes; if you think they need more time, then bake for longer.
If you like to check the internal temperature, it should be about 98°C/208°F.
Video
Notes
I updated the recipe on the 26th of May, 2022, to simplify it with no milk scalding and no levain build. Just feed your starter and use fresh milk!