First, trim the ends off the zucchini. Grate them using a box grater or a food processor with the shredding attachment.
Place a colander in your sink. Add the shredded zucchini and sprinkle with 1 teaspoon fine sea salt. Gently toss with your hands and spread back out to an even(-ish) layer. Let this sit for 10 minutes - this will help extract water from the zucchini. (Do not skip this step.)
Meanwhile, in a large mixing bowl, using a whisk or fork, mix the eggs with the salt, pepper and garlic or garlic powder.
Trim the root ends off the scallions and thinly slice the scallions. Add all of them (white, light green and dark green parts) to the egg mixture.
Once the zucchini is ready, add it to a big piece of cheesecloth or a large, thin, clean kitchen towel. Gather up the corners of the cheesecloth or towel and twist the material into a sack. Squeeze the sack over the sink to extract as much water as possible. Just keep squeezing and twisting, over and over, until barely any water drips out. When you think you've squeezed enough, squeeze a little more.
Add the zucchini to the egg and scallion mixture, then sprinkle over the coconut flour. Stir every together to make sure the zucchini is evenly coated and everything is evenly distributed throughout the mixture.
Heat a large skillet over medium high heat. When hot, add enough avocado oil for a thin layer across the surface of the pan. Give it a minute or so to warm up.
Scoop a scant 1/4-cup of the mixture into the hot pan and gently press it down so it's about 1/2" tall. Continue to scoop the mixture into the pan, making sure the fritters are not touching.
Cook them for 3-4 minutes per side, until browned. Rotate each fritter 180° after about 2 minutes on each side to make sure they brown evenly (sometimes pans won't be as hot toward the edges). I like to flip them using two spatulas (or one wooden spoon and one spatula).
Line a dinner plate with paper towels. Once the fritters are done, drain them on the paper towels for 1-2 minutes, then serve with the yogurt sauce.