Heat 3 cups of water in a pot on the stovetop. Once it comes to a boil, add the cauliflower florets to the water.
Cook the cauliflower florets in boiling water for 3 minutes, then immediately drain them into a colander or use a slotted spoon to take out the cauliflower. Rinse the cauliflower in cold water to stop them from cooking further. The cauliflower should be around 50% cooked.
Toss the par-boiled cauliflower in a little all-purpose flour and keep aside.
In a mixing bowl, add all the ingredients listed under batter., and whisk to form a semi-thick lump-free batter.
Add the cauliflower to the batter and mix such that the cauliflower is well coated in the batter (batter should not drip off the cauliflower too much).
Heat a heavy-bottomed wok with vegetable oil. Once the oil is hot, add a drop of the batter to the oil, if it bubbles and rises to the surface, the oil is hot enough to start deep-frying the cauliflower.
Deep fry the cauliflower in batches, flipping them over midway, so that they are evenly fried. Once the cauliflower is golden-brown, use a slotted spoon transfer to a kitchen paper to absorb the excess oil. Keep aside for later.
Add all the ingredients for the sauce into an empty bottle and shake to mix well. Keep bottle aside.
Heat a wok on the stovetop and add sesame oil. Once hot, add finely chopped ginger and garlic, stir and sauté until aromatic. Add bell peppers and white portion of the spring onions.
Continue to stir on high heat for a minute, and then add the sauces from the bottle. Mix together.
Make a cornstarch slurry by adding 1 teaspoon of cornstarch to 1/3 cup of water. Stir, until lump-free. Add the slurry to the wok and mix it with the rest of the ingredients. Let the sauce thicken slightly. Check the taste and add sugar and salt to season.
Finally, add the deep-fried cauliflower and toss it in the sauce. Turn off the heat, check for seasoning and add salt if need be.
Garnish with toasted sesame seeds and the green portion of the spring onions. Serve with Jasmine rice or noodles.