Pour the sugar and 75ml of water into a very clean saucepan and gently bring to 130°C
Meanwhile, place the miso and 100ml of water into a separate saucepan over a medium heat, stirring occasionally to combine. Bloom the gelatine leaves in cold water for a few minutes until softened, then stir the leaves into the miso until dissolved
Place the egg whites into the bowl of a stand mixer with a whisk attachment and whisk to soft peaks
The next step needs to be done quickly so as to keep the sugar hot. Once the sugar has reached 130°C stir in the miso, then slowly drizzle the mixture into the egg whites (with the whisk still running on full speed)
Once all the miso mixture has been whisked into the egg whites, continue to whisk until it cools down to room temperature (feel the outside of the bowl to check the temperature)
Spoon the marshmallow mixture into a lightly oiled loaf tin (one around 2 litres is a good size, but depending on how you are cutting the marshmallows, any small tin will do). Place in the fridge to set for at least a few hours
To serve, slice the marshmallows into thick rectangles with a knife dipped in hot water. Thread each marshmallow onto a skewer then use a blowtorch, a grill or the flame on your hob to toast and char the sides
