Chop up the cauliflower into small bite-sized florets, and the leaves and stem into 5cm pieces.
Heat a large saucepan a third of the way with vegetable oil, enough to deep-fry the cauliflower.
In a large bowl, combine the 100g cornflour, plain flour, 2 tbsp soy sauce, 1 tsp garlic powder, 1 tsp chilli powder, ½ tsp garam masala with ¼ tsp salt and 150ml of ice-cold water.
Add the florets to the batter and mix well. Gently add each floret into the frying oil, separating them with a spoon or chopsticks if they are getting stuck together. Fry for 3-4 mins until crispy and golden brown, then drain on kitchen paper.
Add the leaves to the batter and fry in the same way, then repeat with the stems.
For the sauce, finely chop the spring onion, separating the whites and greens. Bash the Sichuan peppercorns in a pestle and mortar. Add in the garlic and ginger, then bash to form a paste. Slice up the green pepper and chop the onion into large pieces.
In a bowl, combine the light soy, dark soy, ketchup, sriracha, rice vinegar and 200ml water. In a small cup, combine 1 tsp cornflour with 2 tbsp water.
In a large pan or wok, heat a few large glugs of oil. Fry the spring onions, garlic paste, tomato purée and crispy chilli oil for 2 mins until fragrant. Add in the green pepper and onion, cook for a further 3 mins.
Pour in your sauce and cook on a low heat for 3 mins. Add in the cornflour slurry and heat again until the sauce is bubbling and thickened.
Toss in the fried cauliflower florets and stems. Mix gently so that the sauce coats the veggies. Top with the crispy cauliflower leaves and green parts of the spring onions. Serve with rice or noodles.