In a large mixing bowl, stir together the garlic, shallots, ginger, serrano, cilantro, fish sauce, lime juice, mustard and salt. Add the chicken and mix with your hands until the vegetable mixture is incorporated, but the chicken is still coarsely combined. Form into 6 even patties, 2-inches thick, and set aside on a plate.
Heat a thin layer of oil in a large nonstick skillet. Cook the burgers over medium-high heat until nicely browned and cooked through, about 4 minutes per side. Remove to a plate to rest for 5 minutes.
Serve the chicken burgers in lettuce leaves or on toasted buns and top with a dollop of sriracha mayo. Garnish with fresh cilantro and serve the remaining mayo on the side.