Preheat oven to 350 degrees Fahrenheit and prepare a tray with parchment paper.
In a large bowl, mix together the sugar, avocado oil, flaxseed meal, vanilla extract, and milk until fully combined. If using flaxseed meal, do not let this sit! Immediately add in the dry ingredients: flour, baking powder, and salt and mix until combined. Be very careful to not overmix! This batter will be mixed further and overmixing can create a tough texture.
Separate the batter into 4 equal sections, about a cup each. Note: the flavor ingredients listed are measurements for if the batter is divided in 4. Double, triple, etc. as needed.
Mix in the flavor ingredients (except the strawberry) into each separate section (the plain one will remain). Again, do not overmix!!
For the strawberry, make a jam by bringing all the ingredients to a boil and reducing to a simmer. Cook until very thick. Swirl as much jam as necessary (you probably won't use it all), but do not fully mix it in! This will make the batter too wet. Just very lightly swirl.
Roll out all the dough separately and cut into cookie shapes. Place on the prepared tray and bake for about 15 minutes. Enjoy!