Burgers:
600g coarsely minced beef, not too lean
2 tbsp soy sauce
1 tsp sesame oil
1 egg, beaten
3 tbsp chopped green onions
2 garlic cloves, finely grated
2cm knob ginger, finely grated
1 tsp sugar
Sea salt and pepper
Onion:
3 tbsp vegetable oil
2 onions, halved and finely sliced
2 tbsp mirin
2 tbsp soy sauce
1 tbsp rice vinegar or wine vinegar
Mayo:
3 tbsp whole-egg mayonnaise
1 tsp chilli sauce (eg Sriracha) to taste
4 burger buns
8 soft lettuce leaves
2 tsp sesame seeds
1/2 cucumber, finely sliced
Method
Mix the beef, using your hands, with two tablespoons soy sauce, sesame oil, egg, green onions, garlic, ginger, sugar, salt and pepper. Form into patties and refrigerate for an hour.
Heat two tablespoons vegetable oil in a fry pan and cook onions over medium heat for 10 minutes, tossing well until softened. Add remaining soy, mirin and vinegar and cook for five to 10 minutes more until golden brown. Set aside.
Whisk mayonnaise and chilli sauce. Brush burgers with remaining vegetable oil and grill or pan-fry over medium heat for four minutes on each side until browned (beware of burning). Split burger buns and top base with lettuce leaves and beef burgers. Add a spoonful of chilli mayo and top with soy onions and sesame seeds. Arrange lettuce, cucumber and tomato on remaining bun tops alongside and serve.
