Preheat oven to 400°F. In a large bowl, toss cauliflower and onion with 2 tsp. coconut oil; season with salt and pepper. Roast in a single layer on a parchment-lined baking sheet for 35 to 40 minutes, rotating pan halfway through, until veggies are charred at edges and tender.
Pat salmon dry, season with salt and pepper. In a large nonstick pan over medium-high heat, heat 4 tbsp. coconut oil until lightly smoking. Place filets in pan skin-side down. Gently press the salmon flat. Reduce heat to medium, searing salmon until the skin is golden brown and crisp. Flip filets and remove from heat, allowing fish to continue cooking for 2 to 3 minutes.
Remove salmon to a plate and wipe pan clean. Over medium heat, add 2 tbsp. coconut oil and shallots and sweat 4 to 5 minutes until translucent. Add garlic and lemongrass; sauté 2 minutes. Add curry and stir for 2 minutes until fragrant. Add raisins and soaking vinegar, sugar and coconut milk. Bring to a boil, cooking until reduced by half and the sauce is thickened and glossy.
Pour sauce into a rimmed platter, add vegetables and top with salmon, skin-side up. Garnish with cilantro and mint leaves. Serve immediately with a glass of rosé wine.