Preheat the oven to 425F. Line a baking sheet with parchment paper.
Cook your rice of choice (instructions here). In a large bowl, whisk together the miso, honey or maple, soy sauce, and sesame oil until smooth. Transfer just over half of that (about 4 tablespoons) to a small bowl.
To the large bowl, add the salmon, place them so the flesh side is sitting in the sauce and make sure to rub it on the sides too. Set aside.
To the baking sheet, add the broccolini, oil, and salt and toss to coat, making sure to rub the oil into the heads and all over. Bake for 5-7 minutes or until you notice it’s just beginning to char.
Make 4 spaces on the baking sheet and nestle in the salmon. Scrape and spoon any marinade leftover in the bowl onto the salmon. Bake for 10 minutes or until the broccolini is nicely charred and the salmon is cooked through and easily flakes with a fork.
To the small bowl with the reserved sauce, whisk in the rice vinegar.
Serve the salmon and broccolini with warm rice topped with avocado (if using) and drizzle the sauce all over. Sprinkle with scallions and sesame seeds.