Whisk soy sauce, brown sugar, rice vinegar, ginger, garlic, sesame oil, and cornstarch to make teriyaki sauce.
Set aside half the sauce for glazing and mayo.
Shape ground beef into 4 patties and marinate for at least 30 minutes.
Prepare pineapple rings, lettuce, tomato, and onions.
Mix teriyaki mayo with mayonnaise, reserved sauce, and sriracha.
Preheat grill to medium-high (375–400°F) and lightly oil grates.
Grill patties 4–5 minutes per side, glazing with reserved sauce.
Grill pineapple beside burgers until caramelized.
Toast buns and layer with lettuce, patty, cheese, pineapple, onion, and tomato.
Spread teriyaki mayo on top bun, cover, and serve warm.