1) For dipping sauce, whisk ingredients together and set aside until needed.
2) Combine fish sauce, oyster sauce, diced shallots, garlic, and chiles along with flour in a medium bowl. Stir until mixed well.
3) If you are making your own ground chicken, Remove skin from thighs and/or breasts (1 lb total). If you want, leave some skin on for fat. Pulse in a food processor until slightly chunky.
4) Add ground chicken to other ingredients and stir well to combine.
5) Shape chicken mixture into 8 even patties.
6) Add a drizzle of vegetable oil to a large skillet and cook chicken sausages over medium-high heat for about 6-7 minutes per side until they are cooked through.
7) Once sausages are cooked, add them to clean leaves of lettuce and top with bean sprouts and scallions. Serve with dipping sauce on the side.