Hamburgers with cucumbers and hoisin sauce

Ingredients:

• 650 g ground beef, preferably neck
• Coarse salt and freshly ground pepper
• Vegetable oil, for grilling
• 1/4 cup hoisin sauce
• 6 green onions
• 1/2 tsp. sesame oil, plus more for greasing
• 4 sesame seed buns, cut horizontally into halves
• 1/2 cup mayonnaise
• 1 teaspoon sriracha sauce (Asian chili sauce)
• 12 thin slices of fresh cucumbers

Preparation:

1. Preheat grill to medium-high heat.
2. Form the minced meat into four round patties, each weighing 160 grams and about 2 cm thick. Using your thumb, make a 1.2 mm deep indentation in the center of each patty. Sprinkle the patties on both sides with salt and pepper.
   
   Lightly brush the grill grates with vegetable oil. Place the patties on the grates, indented side down, and cook until charred, about 5 minutes. Flip and continue cooking until slightly firm, about 3 minutes more. The patties will be medium-rare. One minute before the end of cooking, brush the patties with hoisin sauce. Transfer the patties to a serving platter and let them rest for 5 minutes.
3. Brush the green onions with sesame oil, sprinkle with salt, and grill, turning, until softened, 3 to 4 minutes. Cut the onions into 10 cm (4 in) pieces. Place the buns on the grill, cut side down, and grill until golden brown, about 1 minute.
4. Mix mayonnaise, Sriracha sauce, and sesame oil in a bowl and spread the mixture on the buns. Layer the cucumbers, patties, and green onions on the bottom halves of the buns, then top with the remaining halves.