Preheat the oven to 450°F. Line two baking sheets with parchment paper. Spray or rub the parchment paper with cooking oil (don't skip this step, the cauliflower likes to stick to the parchment).
Whisk together all ingredients for the cauliflower batter. Add the cauliflower florets to the batter, a handful at a time, and stir to cover them with the batter. Remove florets, one at a time, let them drip over the bowl momentarily (if needed), and add them to the parchment-lined baking sheets. Add the cauliflower to the oven and set your timer for 15 minutes.
While the florets bake, make the sauce. Start by whisking together all sauce ingredients.
Heat a large, deep, skillet over medium heat and drizzle with oil. Once the oil is hot, add the whites of the green onions. Sauté for two minutes, then add the garlic and ginger. Sauté for another minute or two until onions are completely softened.
Stir the sauce ingredients into the skillet. Simmer for a few minutes until the sauce thickens. Turn off heat until the cauliflower is ready.
After the cauliflower has baked for 15 minutes, remove them from the oven and using a spatula, carefully flip all the pieces over on the parchment. Return the cauliflower to the oven for another *10 to 15 minutes, or until the insides are tender and the outsides are golden browned.
Once the cauliflower florets are done baking, add them, the sesame seeds, and half of the remaining green onions to the skillet with the sauce. Return the heat to medium, and stir until cauliflower is coated and the sauce is reheated. Top individual servings with the remaining green onions and more toasted sesame seeds.