Make the slaw: Use a mandoline or a sharp knife to slice the Armenian cucumber and carrots very thinly, about the thickness of a dime. Place in a mixing bowl with the remaining slaw ingredients and toss to combine. Set aside.
Make the waffles: Preheat a waffle iron to the highest setting and preheat the oven to 200°. Place the chickpeas in a large bowl filled with water. Rub the chickpeas lightly between your palms to loosen the skins, which will float to the top. Skim off the skins using a slotted spoon before draining the chickpeas.
Place the chickpeas in a blender or food processor along with the eggs, milk, olive oil, green onions, garlic, salt, lemon juice, cilantro, parsley, cumin, coriander and cayenne. Blend for 20 to 30 seconds to form a fairly smooth batter. Add the baking powder and flour, and blend on low for a few seconds until combined.
Brush the hot waffle iron with oil or cooking spray and pour in the batter. Cook the waffles for 7 to 10 minutes, depending on the waffle iron, until golden brown. Transfer the waffles directly to a wire rack in the oven to stay warm while preparing the remaining waffles.
Make the harissa yogurt: Combine all the yogurt ingredients in a small bowl and set aside.
Top each waffle with the slaw, drizzle with the yogurt sauce and serve immediately. Leftover waffles can be refrigerated or frozen, and then reheated in a toaster.