1 Rinse salmon, pat dry and cut in half crosswise. Drizzle with teriyaki sauce and season with salt and pepper.
2 Put sesame seeds on a plate, turn the salmon pieces in seeds to coat, pressing firmly to adhere.
3 Heat oil in a non-stick pan and cook the salmon pieces over high heat for about 1 minute on each side.
4 Remove salmon from pan, wrap in aluminum foil and place in the freezer for 30 minutes; this stops the cooking process and makes the fish easier to cut.
5 Meanwhile, squeeze juice from the lemon. Peel the ginger root and garlic, then coarsely chop and grind to a fine paste with 1 pinch of salt in a mortar. Mix lemon juice, rice vinegar, soy sauce and ginger-garlic paste in a shallow dish.
6 Remove salmon from the freezer, add to the ginger mixture and let marinate for 15 minutes, turning several times.
7 Meanwhile, rinse and dry scallions and cut into thin strips.
8 Cut shiso sprouts from the bed with kitchen shears.
9 Remove salmon from the marinade and pat dry. With a sharp knife, cut salmon into thin slices, arrange on plates and drizzle with the remaining marinade. Sprinkle with scallions and shiso sprouts.