Turkey burgers with Asian sauce

Ingredients:

• Extra-virgin olive oil
• 1 onion, diced into 0.5 cm cubes.
• 4 green onions, chopped
• 2 cloves garlic, crushed and finely chopped
• 2.5 cm fresh ginger root, peeled and grated
• 700 g of ground dark turkey meat
• 1 can (220 g) water chestnuts, coarsely chopped
• Half a bunch of fresh coriander leaves, finely chopped
• 1/4 cup soy sauce + more to taste
• 2 tbsp sambal-olek + more to taste
• 4 sesame burger buns
• 4 slices of cheddar
• 1/4 cup mayonnaise
• 4 slices of bull's heart tomatoes
• 4 cups raw red onion
• 8 romaine lettuce leaves

Preparation:

1. Cutlets:
   
   Grease a large skillet with olive oil. Add the onion, season with salt, and heat over medium-high heat. Cook, stirring occasionally, until softened and very fragrant, 7–8 minutes. Add the green onions, garlic, and ginger and cook until fragrant, 1–2 minutes. Turn off the heat and let the onions cool.
2. In a large bowl, combine the turkey, water chestnuts, cilantro, soy sauce, 1 tablespoon sambal oelek, and onion mixture (do not wash the pan; set it aside for the burgers). Use your hands to mix the meat mixture evenly.
3. Prepare a small patty, fry it, and taste it. Add salt to the meat mixture if necessary. Form it into 4 equal patties.
4. Grease a frying pan with olive oil and heat over medium-high heat. Place the patties in the pan, being careful not to overcrowd. Cook for 5–6 minutes on each side.
5. Preheat oven to grill mode.
6. Transfer the patties to a rack set on a baking sheet. Place the buns, cut-side up, on the same rack. Place on the bottom rack of the oven and broil until the patties are set and the buns are golden brown, 2 to 3 minutes. Remove the buns from the rack and top the patties with the cheese. Return to the oven and broil until the cheese is melted, about 1 minute.
7. In a small bowl, combine the mayonnaise with the remaining 1 tablespoon of sambal oelek. Lightly coat each bun half with the spicy mayonnaise. Place a patty on each bun half, then top with a tomato slice, onion, and lettuce leaf. Top the burgers with the top bun halves, press down, and enjoy!