Add the flour, salt and baking/bi-carb soda to a medium mixing bowl. Whisk to combine and set aside.
In a large mixing bowl or the bowl of a stand mixer fitted with the paddle attachment, add the sugar, butter and coconut oil. Using a hand mixer or stand mixer, beat on low speed until just combined. Scrape down the sides and increase the mixer speed to medium-high. Cream the sugar, butter and oil together until light and fluffy - about 3-5 minutes.
Scrape down the sides of the bowl and add the eggs, apple cider vinegar and vanilla extract. Mix on medium speed until combined, smooth and homogenous.
Add the dry ingredients and mix on low speed until just combined. Cover the bowl with plastic and move to the refrigerator to chill for at least 1 hour and up to 3 days.
Preheat oven to 180°C/350°F. Line 2 baking sheets with parchment paper. In a small dish or ramekin, whisk together the cinnamon with 50g (¼ cup) of sugar.
Remove the cookie dough from the refrigerator and scoop into 2 tbsp (about 25g/1oz) sized balls. Use your palms to roll each piece of dough into a spherical shape and then roll each dough ball in the cinnamon sugar. Place on the prepared baking sheets, ensuring there is at least 5cm (2in) of space between each cookie. Press lightly on each dough ball to flatten it slightly. (See note 2)
Bake the cookies, one sheet at a time, until soft and tender in the middle and dry and lightly crisp around the edges, 8-10 minutes. Transfer to a wire rack and allow to cool completely.
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Notes
Use the weight measurement of salt rather than the volumetric measurement if at all possible. Different brands and types of salt can vary, so going by weight is going to be the most consistent option.
At this point, the cookie dough balls can be moved, uncovered, into the freezer and frozen solid. Once frozen, transfer the balls to an airtight container or freezer bag and store in the freezer for up to 3 months. Bake from frozen, ensuring to add 2 minutes to the cook time.