Preheat the oven to 425°F (220°C) and line a baking sheet with parchment paper.

Cut the cauliflower into bite-sized florets and pat them dry to remove excess moisture.

In a large bowl, whisk together the chickpea flour, cornstarch, garlic powder, onion powder, salt, and pepper. Gradually add 1/2 cup of water until a smooth batter forms.

Toss the cauliflower florets in the batter until each piece is evenly coated.

Spread the coated florets in a single layer on the prepared baking sheet and drizzle with oil.

Bake for 20 to 25 minutes, flipping halfway through, until the florets are golden and crispy.

While the cauliflower bakes, combine the tamari, rice vinegar, maple syrup, sesame oil, ginger, and garlic in a small bowl.

Heat the sauce mixture in a small saucepan over medium heat until it begins to simmer.

Stir together 1 tablespoon of cornstarch and 2 tablespoons of water in a small bowl to make a slurry, then whisk into the simmering sauce. Cook for 1 to 2 minutes until thickened.

Transfer the baked cauliflower to a large bowl, pour the sticky sauce over it, and toss gently to coat.

Garnish with sesame seeds and sliced green onions before serving.