Combine marinade ingredients and pour over chicken. Marinate at least 30 minutes or overnight. Grill until cooked through, 4-6 minutes per side depending on the thickness.
Cube or cut to fit the buns. Serve warm or at room temperature.
Make Sriracha Mayo
Combine mayonnaise and Sriracha. Set aside.
ASSEMBLY
Lightly toast buns. Spread one side with butter and the other with the Sriracha-mayo.
Add lemongrass chicken, cucumber, carrot and cilantro. Top with onion and jalapeno if using. Serve warm.
Notes
I always plan to make these subs with leftover Lemongrass Chicken.