Miso, mirin, and sriracha are pretty easy to find. Try Central Market or Whole Foods. Or visit an Asian grocery--they usually have cool stuff for not a lot of money!
1/4 cup white miso
1/4 cup mirin (sweet Japanese rice wine)
2 tablespoons unseasoned rice vinegar
2 tablespoons minced green onions, plus more for garnish
1 1/2 tablespoons minced fresh ginger
2 teaspoons sesame oil
1 teaspoon sriracha (Asian hot sauce), or to taste
4 (6-ounce) salmon fillets
Sesame seeds, toasted, for garnish
In a medium bowl, whisk together all the ingredients except the salmon until blended. Lay te salmon fillets in a single layer in a baking pan or dish. Pour the marinade over and turn the salmon fillets to coat them. Refrigerate for at least 30 minutes.
Heat the broiler. Line a baking sheet with foil. Spray the foil with nonstick spray. Remove the salmon from the marinade, using a rubber spatula to scrape off the excess marinade. Arrange the salmon skin side up on the baking sheet. Broil until the skin is crisp, about 6 minutes, then carefully flip the fillets and broil until the salmon is cooked through but still slightly darker pink in the center, about 7 minutes more. (Cook the greens--I like baby bok choy or Chinese water spinach--now.)
To plate, spoon a bed of rice just slightly "north" of the center of the plate. Top with greens, then lay the salmon at angle pointing down towards the bottom right of the plate.