Begin by preheating your oven to 200 degrees Fahrenheit to keep the first batch of burgers warm as you cook.

To prepare the burgers, coat a large sauté pan with olive oil and add the diced onions. Season them with salt and set the heat to medium-high. Cook the onions until they become soft and fragrant, which should take about 7 to 8 minutes. Add the minced garlic and continue cooking for an additional 1 to 2 minutes before turning off the heat. Allow the mixture to cool.

In a spacious mixing bowl, combine the ground turkey, soy sauce, sambal oelek (if using), grated ginger, chopped water chestnuts, cilantro, and the cooled onion and garlic mixture. Reserve the sauté pan for cooking the burgers later. Incorporate one-quarter to one-half cup of water to keep the patties moist. Using your hands, mix all the ingredients thoroughly until well combined.

To ensure proper seasoning, create and cook a small test patty. Taste it to determine if any adjustments are necessary. If it lacks salt, you can either add more soy sauce or sprinkle a little additional salt.

Once the burger mixture is adequately seasoned, form it into four equal-sized patties.

Recoat the sauté pan with fresh olive oil and heat it over medium-high heat. Carefully place the patties into the pan, ensuring not to overcrowd it. If needed, cook the burgers in batches. Allow the patties to cook for 5 to 6 minutes on each side. If you are using cheese, add a slice to each burger during the last minute of cooking to let it melt.

Toast the burger buns using a broiler or toaster. Spread a thin layer of the sambal mayo on each side of the buns. Assemble the burgers by placing one patty on each bottom bun and topping them with slices of tomato, onion, and butter lettuce. Close each burger, give it a gentle press, and enjoy your delicious creation!