Roast the cauliflower: Preheat oven to 415F. Toss cauliflower with olive oil, turmeric, and 1/2 tsp salt. Line a baking sheet with parchment paper.  Spread florets across baking sheet and roast for 25 minutes, flipping once. Cauliflower should be tender with moderate browning.

Make sauce verte: Place all ingredients plus a large pinch of salt in a food processor or blender, starting with 2 Tbs olive oil. Blend until a coarse paste forms, adding more olive oil or a splash or water if too thick. Taste and season with salt and pepper.

Saute chard, finish cauliflower and cook fish: Chop chard leaves roughly and slice stems. Heat a large skillet with olive oil over medium heat. Add stems and cook for 2 minutes. Then add garlic, leaves and a large pinch of salt. Cook til tender, stirring occasionally, about 3-4 minutes longer. Turn off heat and leave in pan until ready to serve.

Meanwhile, heat 2 Tbs butter in a nonstick skillet over medium-high heat. Cook til light brown and fragrant, about 3-4 minutes. Transfer roasted cauliflower, brown butter and preserved lemon into a large bowl and mix gently to combine.

In the same pan, heat 2 tsp olive oil and 1 tsp butter over medium-high heat. Season fish with salt and pepper. Turn heat down to medium. For halibut, sear 2-3 minutes per side. For salmon, try 4-5 minutes per side, pending thickness. And for tuna, leave heat at medium-high and sear 1-2 minutes per side. Slice fish into serving pieces and pour over pan juices.

To serve: Give cauliflower once last stir. Place some cauliflower on half the plate, chard on the other. Top with fish and a drizzle of sauce verte. Serve more sauce verte at the table.