Heat oven to 350℉. Line a baking sheet with parchment paper.
In a large bowl, stir together the oats, flour, sugar coconut, and salt. In a heavy saucepan over medium heat melt the butter and honey. In a small bowl, combine the baking soda and boiling water, then add this to the butter mixture. It will foam and increase in size. Pour into the flour mixture and stir well to combine.
Roll dough into golfball sized balls and very lightly flatten them between your hands. Place on the prepared sheet about 1 inch apart, place in the oven, and bake for 10-15 minutes. Remove from heat, gently remove to a wire rack, and let cool.
Notes
I read one recipe that exhorted that you must follow the recipe EXACTLY or else it wouldn’t be a true Anzac biscuit — agree, sure, but I didn’t have golden syrup so used New South Wales (local!) honey instead. Use gluten-free oat flour to make these gluten-free and/or substitute coconut oil for the butter (plus maple syrup for the honey) to make vegan.