Make sesame cucumbers: Put the sesame seeds in a small dry skillet over medium heat. Cook, tossing, for 2 to 3 minutes, until toasted. Let cool. In a medium bowl, combine the cucumber, jalapeño, lemon juice, oil, and salt. Stir in dill and sesame seeds.
Put the whole salmon fillet in a large ziptop plastic bag. In a small bowl, combine the soy sauce, honey, orange juice, and ginger. Reserve 3 tablespoons of the mixture and set aside. Pour the remaining mixture over the salmon. Squeeze out the air and seal the bag. Refrigerate for 15 minutes to let marinate (flip the salmon over halfway through so both sides marinate evenly).
Preheat the broiler (with the oven rack about 4 inches from the top). Line a rimmed sheet pan with aluminum foil.
Place the salmon on the prepared pan and discard the marinade. Broil for about 5 minutes, or until the top of the salmon begins to char. Pull the pan out and spoon half of the reserved soy sauce mixture over the salmon. Broil for 1 minute, then add the remaining soy mixture and broil for 1 minute more. The top should be nice and charred but not burned.
You can check for doneness by inserting the tip of a paring knife into the thickest part of the salmon. If the salmon flakes easily but still has a slightly darker orange center (medium-rare to medium), then it’s done. If not, or if you like your salmon cooked more, then broil 1 to 2 minutes more. Cut into 4 pieces and serve with the sesame cucumbers.