Preheat the oven to 425°F.
Rinse and pat dry the salmon fillet. Season both sides with salt and pepper.
Heat a non-stick skillet over medium-high heat. Once hot, sear the salmon skin-side down (if present) for about 3-4 minutes until a crust forms, then flip and cook for another 2-3 minutes. The salmon should be just cooked through.
While the salmon cooks, prepare the vegetables. Break the broccoli into florets and toss with a pinch of salt, pepper, and half the olive oil. Spread them on a baking sheet.
Roast the broccoli in the preheated oven for about 10-12 minutes until tender and slightly charred.
For the cauliflower mash, steam the cauliflower florets until very tender, about 8-10 minutes. Meanwhile, lightly sauté the garlic clove in the remaining olive oil until just fragrant.
Transfer the steamed cauliflower to a bowl and add the sautéed garlic. Mash until smooth, adding a pinch of salt and pepper to taste.
Plate the dish by placing a generous scoop of garlic cauliflower mash, arranging the roasted broccoli beside it, and topping with the seared salmon fillet.
Serve immediately and enjoy your well-balanced, nutritious dinner.