Step 1

Arrange a rack in the middle of the oven and a second rack 6-inches from the broiling element. Heat the oven to 400ºF. Line a rimmed baking sheet with a sheet of aluminum foil, fold the foil in half lengthwise so there is a crease in the center, then unfold the foil.

Step 2

Make the glaze: Thinly slice the white and light green parts of 4 scallions, keeping them separate. Reserve the greens for garnish, and place the whites in a medium bowl. Grate 2 garlic cloves, and peel and grate a 2-inch piece of ginger until you get 1 teaspoon; add both to the scallions whites. Add 1/4 cup olive oil, 1/4 cup tamari or soy sauce, 1/4 cup packed brown sugar, the juice of 1 of the lemons (about 2 tablespoons), and 1/4 teaspoon ground black pepper. Whisk until thoroughly combined and the sugar is mostly dissolved.

Step 3

Generously season the salmon fillet all over with salt and pepper. Place skin-side down on the foil next to the foil crease.

Step 4

Pour the glaze all over the salmon, lifting the salmon to get some of it underneath. Fold the foil over the salmon, then pinch and seal it on all three sides to create a closed packet.

Step 5

Roast on the middle rack until the salmon is an opaque pink outside, and a light pink color inside with flesh that easily flakes, 15 to 20 minutes (15 minutes will be on the medium-rare side and 20 will be cooked through). Meanwhile, cut the second lemon into wedges and coarsely chop 1/2 cup fresh cilantro if desired.

Step 6

Remove the salmon from the oven. Turn on the broiler. Use a fork and knife to carefully open the foil packet by cutting it down the middle and pushing the foil to the sides. Use a spoon to baste the salmon with the liquid in the packet. Broil on the upper rack until the top is dark golden brown, 1 to 3 minutes, depending on the strength of your broiler (keep an eye on it).

Step 7

Cut the salmon into serving pieces — the meat will easily lift from the skin. Top with the scallion greens, black pepper, and cilantro if desired. Serve with the lemon wedges.