Preheat oven to 350°F/177°C. Line a baking sheet with parchment paper or silat.
Combine butter and 1 cup of sugar in a mixing bowl and mix on medium-high speed until creamed, around 2 minutes.
Add the flax egg and mix until just combined.
Reserve one tablespoon of the strawberry powder. Add remaining strawberry powder and pink food coloring (if using) to the mixing bowl. Mix on low speed to combine.
Whisk together flour, salt, and baking soda. Gradually add the flour to the dough. Mix on low speed until just combined.
Combine the reserved sugar (1/4 cup) and reserved strawberry powder (1 tablespoon) to create a rolling mixture.
Scoop dough and roll into balls. Roll the balls in the strawberry powder mixture. Place on a pan, roughly 2 inches apart.
Bake in the center rack of the oven for 10 minutes. Remove from the oven and allow the cookies to set on the pan for 5 minutes, then transfer to a wire rack to cool completely.