Preheat barbecue to medium high heat or oven to 375 degrees.

In a small sauce pan, combine the tamari, lemon juice, rice wine, garlic, ginger, and agave syrup, and bring to a bowl.

Mix the cornstarch with a tablespoon of water in a separate bowl. Then pour into the boiling tamari mixture. Bring mixture to a boil once again, and then lower to a simmer for 2-3 minutes until it becomes thick. Remove from heat.

Put 2 tablespoons of the thickened tamari mixture to the side. Using a basting brush or the back of a spoon, spread the rest of the mixture on the top of the salmon filet(s).

Place the salmon on the barbecue or on a baking sheet and into the oven, and cook for 7-8 minutes.

Sprinkle the scallions and sesame seeds on top of the salmon, and cook on the barbecue for 2-3 more minutes or place under the broiler for 2-3 minutes.

Serve immediately with the remaining teriyaki sauce on the side.