Step-by-step · 35 minutes
Fill a small pot with 1 cup of water; cover and heat to boiling on high. Wash and dry the fresh produce. Trim off and discard the stem ends of the green beans. Peel and finely chop the garlic. Grate the ginger on the small side of a box grater. Thinly slice the scallions, keeping the white and green parts separate.
Once the water is boiling, add the rice and a big pinch of salt. Stir once, then cover and reduce the heat to low. Cook 12 to 14 minutes, or until the water has been absorbed and the rice is tender. Turn off the heat and fluff with a fork; season with salt and pepper to taste. Cover to keep warm until you are ready to plate.
Pat the salmon fillets dry with paper towels; season on both sides with salt and pepper. In a large pan, heat a drizzle of olive oil on medium-high until shimmering. Add the fillets skin side down and cook 4 to 5 minutes, pressing gently so the skin stays flat, until crisp and released from the pan. Flip and cook 2 to 3 minutes more.
Transfer the cooked salmon to a plate; loosely cover with foil to rest. Wipe out the pan, then heat on high until very hot. Add the green beans in a single layer and cook, without stirring, 2 minutes, or until charred in spots. Add the garlic, ginger, and white parts of the scallions; season with salt and pepper. Cook, stirring occasionally and scraping up any fond, 3 to 4 minutes, or until the beans are crisp-tender and the pan is nearly dry. Turn off the heat. Taste, then season with salt and pepper if desired.
In a bowl, combine the white miso, the softened butter, and half the lemon juice. Whisk vigorously until completely smooth and glossy, about 1 minute; if the butter is still firm, let it sit at room temperature 2 minutes and whisk again. Taste, then season with salt and pepper if desired.
Divide the cooked rice between two shallow bowls. Top each with a salmon fillet and spoon the miso butter over the warm fish so it melts into a glaze. Add the blistered green beans alongside, then finish with the green parts of the scallions, the toasted sesame seeds, and the remaining lemon juice. Serve right away. Enjoy!
I let the miso butter sit out while the rice cooked and it whisked together in seconds. Spooning it on straight off the heat is the whole trick — it turns into a glaze instead of sitting in a lump.
Get the pan properly hot before the beans go in and leave them alone for the first two minutes. Mine went from dull green to blistered and sweet, and the fond from the salmon picked up all the ginger.
Swapped the salmon for two arctic char fillets from the market and kept every other step the same. Six minutes total in the pan was plenty; the skin still crisped up beautifully.
Doubled the rice and packed the leftovers for lunch with a spoonful of the miso butter stirred through. Reheated better than I expected — the scallion greens go on after, not before.