Preheat the oven to 425 degrees F.: You should notice the oven warming evenly, and preheating ensures quick caramelization of the vegetables. The hot environment encourages the Maillard reaction on the surfaces of both the broccoli and brussels sprouts , producing those fragrant roasted notes you want. A common mistake is not waiting until the oven reaches temperature, which leads to limp, pale veg.
Spread the broccoli and brussels sprouts out on a baking sheet. Toss well with the olive oil. Toss with a big pinch of salt and pepper. Sprinkle on the parmesan and pine nuts. Roast for 15 to 20 minutes, tossing once or twice during cook time to make sure the nuts don’t burn.: As the vegetables roast you will hear a gentle crackle and see edges turn golden brown, with nutty aromas from the pine nuts . Turning them once helps expose all sides to heat for even browning, and the parmesan will melt then crisp slightly, adding savory notes. Watch the pine nuts carefully, because they toast quickly and can go from perfect to bitter within a minute.
While the vegetables are roasting, make the salmon. Season the salmon filets all over with salt and pepper.: The seasoning step primes the salmon to develop a flavorful crust and helps the glaze adhere. When you touch the fish it should feel slightly tacky after being seasoned, which helps searing. Over seasoning is the usual error here, so start with modest salt and adjust later.
Heat a cast iron skillet over medium heat. Add the butter. Once melted, stir in the garlic and cook for 30 seconds.: You will smell the butter turn fragrant and the garlic release a light savory perfume almost immediately. This brief cook softens the raw edge of the garlic while infusing the fat, which becomes the flavor base for the glaze. Letting the garlic brown is the common mistake, because once it darkens it turns sharp and bitter.
Stir in the maple syrup, pomegranate molasses and water. Bring the mixture to a boil then reduce it to a simmer. Add the salmon into the skillet. Spoon the glaze over top of the salmon every 30 seconds or so. Cook and spoon it over for about 5 minutes.: As the liquids hit the hot pan you will see them reduce and thicken into a glossy glaze, filling the kitchen with sweet tart aromas. Basting transfers that concentrated flavor onto the surface of the salmon , promoting a shiny, sticky finish. If you skip frequent spooning the glaze can reduce unevenly and leave parts of the fish dry.
Transfer the entire skillet, uncovered, to the 425 degrees F oven. Roast for 5 to 10 minutes, until the salmon is just cooked through, is opaque and pink and flakes easily with a fork. By this time, the roasted vegetables should be done too!: In the oven the heat will finish cooking the fish gently while encouraging the glaze to set into a lacquered surface. Look for the fish to turn opaque and to separate into flakes with gentle pressure, and for the vegetables to show golden edges. Overcooking here is the main pitfall as salmon will become dry quickly, so check early and often.
Remove the salmon from the oven and sprinkle with the parsley and pomegranate. Serve immediately with the vegetables!: The finishing hit of fresh herbs and ruby arils adds aroma and bright acidity that cut through the glaze and fat. Visually the dish pops, making each plate look composed. If you let it sit too long the glaze will lose its shine and the pomegranate will soften, so serve right away for best results.