Add the yeast, honey, and warm (not hot) water to a large bowl. Mix with a fork and allow to sit for 5-10 minutes if using instant yeast, and 10-15 minutes if using active dried yeast. When ready, the yeast will look foamy with small bubbles.
Whisk in the apple cider vinegar and extra virgin olive oil. Sprinkle the sea salt into the bowl, along with 3 cups of the gluten-free flour. Use a fork to begin mixing in the dry ingredients.
Generously flour your work surface with about ¼ cup of gluten-free flour. Scrape the dough from the bowl onto the floured surface. Top the dough with about ¼ cup of additional flour and flour your hands. Gently push the dough together and begin to knead in the extra flour. Add flour as needed. The dough is done when it can be formed into a smooth ball without any sticky spots. In my testing, I typically used a total of 3½-4 cups of the Mulino Caputo Fioreglut gluten-free flour. If you are using a different flour mix, it may absorb more or less.
Once your dough ball is formed, generously pour olive oil in a large bowl. Place the dough ball in, drizzle with a little more olive oil, and cover with a kitchen towel. Let rise in a warm place for 1 hour - 1 hour 15 minutes.
You will notice the dough has grown quite a bit. Generously spread olive oil all over the bottom and sides of a 9x13 inch rimmed baking sheet. You could also use a 9x13 inch baking dish. Scrape the dough onto the baking sheet and use your hands to spread it out to the entire surface area. Drizzle olive oil over the surface and use your fingers to dimple the surface of the dough. Cover with a kitchen towel and allow to rest for 30-45 minutes. When there's 15 minutes left, preheat the oven to 450°F.
Once rested, re-dimple the dough and add more olive oil if needed. Top with your toppings of choice such as: fresh or dried rosemary, olives, roasted red peppers, cherry tomatoes, roasted garlic, etc. Sprinkle with a bit of flakey sea salt (we'll add more later).
Bake for 17-20 minutes until your focaccia is lightly golden. Immediately sprinkle with more flakey sea salt. Allow to cool in the pan for 20 minutes. Slide a large spatula under the dough to release any stuck spots from the pan, and transfer to a wire rack to cool. Enjoy warm after 30 minutes, or allow to cool completely for about 2 hours. Slice with a serrated bread knife or kitchen shears. Enjoy your homemade gluten-free focaccia! See the notes below for serving and storage suggestions.