To make the crispy onions, peel and thinly slice the shallots or onion into rings. Heat a good splash of oil in a pan and slowly fry the shallots for 15 minutes, until golden. Remove with a slotted spoon and set aside on kitchen paper to crisp up.
Trim away the cauliflower stalk, then boil the cauliflower whole in a pan of salted water over a medium heat for 3 minutes, then drain and leave to cool.
Next rub in the chilli, sea salt and black pepper, and drizzle with a little oil. Leave to one side.
For the pesto, toast the nuts in a dry pan over a low heat until golden, then either bash with a pestle and mortar or blitz in a food processor until combined.
Pick and add the herbs with a pinch of salt and blitz or bash again until you have a thin paste. Season with lemon juice, oil, salt and pepper, and set aside.
Heat the cannellini beans and a couple of tablespoons of their liquid in a pan over a low heat for 10 minutes, or until warmed through. Mash and stir through 1 to 2 tablespoons of the pesto.
Preheat a griddle pan over a high heat.
Quarter the cauliflower and char on the griddle for 6 to 8 minutes, or until golden and charred.
Divide the mash between four plates and top with a wedge of cauliflower, a drizzle of the herb oil and the crispy shallots.