Make the Teriyaki Marinade: In a small saucepan, whisk together the low-sodium soy sauce, pineapple juice, brown sugar, grated ginger, minced garlic, and sesame oil. Bring to a simmer over medium heat until sugar dissolves (3-4 minutes).

Marinate the Salmon: Pour half of the warm sauce into a shallow dish and let cool for 5 minutes. Add the salmon fillets and marinate for 15-30 minutes at room temperature.

Prepare the Glaze: In a small bowl, mix cornstarch and cold water to create a slurry. Whisk the slurry into the remaining sauce in the saucepan. Simmer over medium heat, stirring, until the sauce thickens, about 2-3 minutes. Remove from heat.

Preheat and Clean the Grill: Preheat grill to medium-high (400-450°F). Clean the grates thoroughly. Use tongs to wipe the grates with a paper towel dipped in high-heat oil.

Grill the Salmon: Place salmon fillets skin-side down on the hot, oiled grates. Close lid and cook for 4-6 minutes, until the skin releases easily.

Grill the Pineapple and Finish Cooking: Flip the salmon carefully. Place pineapple rings on the grill. Brush the top of the salmon with the thickened glaze. Close lid and cook for another 3-5 minutes, or until salmon reaches 130-135°F.

Serve Immediately: Remove salmon and pineapple from the grill. Serve topped with a pineapple ring, extra glaze, sliced scallions, and toasted sesame seeds.