Preheat the oven to 220°C/200°C fan/425°F/gas mark 7.
Mix the oil and cumin seeds together in a bowl.
Put the cauliflower on a baking tray and pour the cumin oil over the top of the florets. Roast the cauliflower in the oven for 20–30 minutes until soft. For the last 5 minutes of cooking, add the cauliflower leaves to the baking tray and roast those too.
To make the dip, put the Sichuan peppercorns, chilli, ginger, garlic and sesame seeds in a heatproof bowl.
Heat the vegetable and chilli oil in a small pan. When hot, pour the oil over the Sichuan peppercorn mixture. It should crackle and pop. Add the soy sauce and sesame oil and whisk in the peanut butter. You might need to loosen the dip with a little water to give it more of a dressing consistency.
For the topping, mix all the ingredients together, either chopping by hand or using a food processer, to a fine crumb and set aside.
To serve, spoon a generous pool of peanut dressing onto each plate and top with the roasted cauliflower. Garnish with the peanut and breadcrumb topping and, lastly, the Thai basil leaves and spring onions.