Begin by cooking the rice according to the rice package instructions. While rice is cooking, prepare your cauliflower.
Preheat oven to 450 F. In a shallow mixing bowl, combine chickpea flour and water, whisking together until thick and gooey. This will act as your binder between the cauliflower and flour mixture. In a separate shallow bowl combine flour, salt, pepper, and garlic powder. Pour 1 tablespoon of cooking oil into a heavy bottom baking dish or large cast-iron skillet. Dip each floret into the chickpea flour mixture until completely submerged, then dip it immediately into the flour mixture, coating thoroughly. Place the battered cauliflower in the baking dish and repeat until all the cauliflower is covered.
Bake for 10 minutes. Pull out of the oven, flip cauliflower over and brush or spray the additional 1 tablespoon of oil on the top of the florets. Bake for another 10 minutes.
While cauliflower is baking, make your sauce. Begin by heating up sesame oil in a small pan. Add garlic and ginger and sauté for 1-2 minutes until fragrant. Whisk in remaining ingredients EXCEPT for the cornstarch and water and simmer for 2 minutes.
In a small bowl, whisk together cornstarch and water. Add to sauce ingredients and bring to boil. Reduce heat to a simmer and simmer for 5 minutes until sauce is thickened and cornstarch has completely dissolved.
Pour all but 2 tablespoon of sauce over the battered cauliflower and bake for another 5-10 minutes until sauce is sticky and thick.
Serve immediately over cooked rice. Top with sesame seeds, green onion, and remaining sauce.