Pat vegan salmon fillets dry.
Brush fillets with olive oil, salt, and pepper; set aside.
In a saucepan, combine soy sauce, sugar, garlic, ginger, vinegar, and sesame oil.
Simmer 3 minutes, stir in cornstarch slurry, cook until thick.
Preheat grill to medium-high; oil grates lightly.
Grill salmon 6–7 minutes per side until charred.
Brush teriyaki glaze over fillets during final minute.
Remove, drizzle extra glaze, and serve hot.