Preheat the oven to 425°F (215°C) and line a muffin tin with paper liners or grease it well.
Use a box grater to finely grate the zucchini. No need to peel the zucchini. If you find your zucchini is quite moist, place the grated zucchini in a tea towel or a paper towel and squeeze out any moisture.
In a large bowl, place the whole-wheat flour, coconut sugar, baking powder, baking soda, cinnamon, and sea salt; whisk together well. Push the flour mixture to the sides of the bowl to make a 'well' for the wet ingredients.
In the flour bowl, place the wet ingredients in the 'well': the yogurt, eggs, orange juice, and orange zest. Then mix just these wet ingredients as best you can without stirring in the flour mixture. Once the eggs are beaten into a yellow mixture with the yogurt, add the grated zucchini to the bowl and use a spatula to fold the flour mixture into the wet mixture just until mixed; do not overmix.
Divide the batter evenly into the muffin tin. I make this batter into 11 large muffins. Bake at 425°F (215°C) for 8 minutes, then turn the oven down to 375°F (190°C) and bake for another 7-8 minutes until the muffins are fully baked. Allow the zucchini muffins to cool in the pan for 5 minutes, then transfer to a rack to finish cooling.