1. Place the walnuts in a food processor and pulse to a bread crumb-like texture. Pour them into a large bowl. Place half the cauliflower florets in the food processor and pulse until they’re a couscous-like texture. Add to the walnuts and repeat with the remaining florets.
2. Add the lemon juice, olive oil, mint, and preserved lemon to the cauliflower mixture and stir to combine. Season with a pinch of salt and add more olive oil and lemon juice to taste, if desired.

Make the cauliflower purée

1. In a small saucepan, bring the cauliflower, milk, and salt to a boil. Simmer until the cauliflower is very tender, 3 to 5 minutes. Drain the cauliflower, reserving the milk. Place the cauliflower in a blender, add the butter and lemon juice, and process until smooth, adding a little reserved milk if necessary to attain a purée. Season with salt and pepper. Cover to keep warm while you cook the fish.

Fry the fish

1. Pat the fish dry and season on both sides with salt. Heat the glug of olive oil—just enough to coat the surface in a frying pan over medium heat. Once hot place the fish in the skillet, skin side down (or, if the fish has no skin, the side that had the skin), until crisp and golden, about 2 minutes. Flip the fish and continue to cook until the fish is opaque throughout, another 2 to 3 minutes, depending on the size of the fish.
2. To assemble, place a dollop cauliflower purée on each plate,add the cauliflower couscous, and place a fish fillet, on the side. Enjoy